Our Demons Are Different

"Faustus How comes it, then, that thou art out of hell?

Mephistophilis Why, this is hell, nor am I out of it:"

- Christopher Marlowe, Doctor Faustus

Demon
 * 1) An evil spirit or supernatural being (generic)
 * synonyms: devil, fiend
 * 1) Fallen Angels who rebelled against God (Christian)
 * ...or, the disembodied spirits of formerly-living half-Angel/HalfHumanHybrids (called "Nephilim", meaning "Fallen Ones" and "Marvelous Ones")
 * 1) a lesser or inferior god or spirit (Greek). See Obake/Youkai, Our Fairies Are Different, Our Genies Are Different.
 * 2) a daemon; ask Aristotle for the details. See Good Angel, Bad Angel, Spirit Advisor.

Where do your demons live?
 * In Hell (especially of the Fire and Brimstone variety)
 * In a more generic Underworld Beneath the Earth
 * ...such as the Abyss
 * Another plane of existence altogether
 * Everywhere

Who do your demons work for?
 * Satan or perhaps some other religious antichrist equivalent
 * Any Big Bad who knows the incantation to summon and control them, or even the good guys.
 * Themselves
 * Even bigger and badder demons (e.g. Demon Princes from D&D)
 * An incomprehensible unknown force (the horror!)
 * The Great Old Ones or Other Gods

What do they look like?
 * Pretty indistinguishable from Humans, except maybe Pointy Ears, unnatural skin colors, horns and a tail, and/or Cute Little Fangs.
 * Indistinguishable from angels.
 * May or may not resemble vampires.
 * Human men dressed in expensive looking black suits with a goatee and/or thinly trimmed moustache.
 * Human women scantily clad in black leather.
 * Monsters with red skin, horse or goat hooves, horns on their head, a pointed tail, and may or may not be holding a pitchfork.
 * Horrific Living Shadows with Glowing Eyes of Doom.
 * An Eldritch Abomination
 * Anything they want.
 * Or they may not be able to take physical form on this world, preferring Demonic Possession.
 * Any or all of the above at once and then some (multiple races/breeds). Also often include Demonic/Devilish beasts/monsters such as the ever-popular Hell Hound and Hell-themed versions of natural animals or mythological monsters.

What is the difference between demons and devils?
 * None; the two names are synonymous.
 * Satan is the Devil, demons are his minions.
 * A devil is a type of demon.
 * Devils are tiny, like goblins or gremlins, whereas demons are big and muscly (or overly elaborate and shocking in appearance).
 * Devils are charming while demons are plain ugly as sin (or vice versa).
 * Demons are Chaotic Evil; devils are Lawful Evil.
 * Demons are monstrous eldritch abominations; devils are humanoid fallen angels.
 * No real difference, they just each have their own hellish planes of existence.
 * Whatever the hell the author wants it to be, and he may as well drop daemons in there just for the Hell of it.
 * Demons are interdimensional travellers, Devils (or rather, Deveels) are Cutthroat Merchants.

What are your demons' common powers?
 * Shapeshifting
 * Possession
 * Temptation
 * Pyrokinesis
 * Hellfire
 * Feeding off negative emotions
 * Avatar Projection
 * Unlimited, since they can do or give you anything you want... in exchange for your soul.
 * Or just plain screwing with reality as we know it (generally the way of Eldritch Abominations).

What are your demons' common weaknesses?
 * Cannot enter a Church
 * A cross or holy water
 * The Power of Love (and or The Power of Friendship)
 * Light
 * Scorn
 * Exact Words
 * Magical or holy weapons
 * Good old fashioned steel or firepower
 * Closing the portal from whence they came upon this world (through magical means or otherwise). Could be immortal and thus invulnerable when used in conjunction with this trope (or not).
 * Exorcism by a priest or other holy individual
 * A pentagram, used to ward off or contain demons and evil spirits.
 * A line of salt, chalk or other powdered substance.

Miscellaneous
 * Are they naturally evil, or can they turn good?
 * What are their motives?
 * Can humans become demons?
 * And what about all those half-Half Human Hybrids?

There's no doubt about it. No matter what you choose, Your Demons Are Different.


 * If the source is Japanese, and the demons are really different, the reason may be simply that, in translation, the word "demon" is being substituted for a completely different word, Youkai, which really doesn't have a correlating concept in English. "Faerie creature" is probably closer when it comes to traditional function in folklore (in fact, on the occasions where "fae," etc. is translated into Japanese, the term will probably contain the same "you" as "youkai"), but "demon" sounds more likely to kick ass, despite faeries being pretty damn scary.
 * And even if they don't use youkai, Japan still has a lot of words that get translated as "demon." Mazoku, Akuma...

Specific Types:
 * Horny Devils
 * Satan
 * Demon Lords and Archdevils
 * The Legions of Hell
 * Fallen Angel
 * Big Red Devil
 * The Heartless sometimes get classed as demons depending on the work.

Anime and Manga

 * In Beelzebub, The Demons look More "Human-Like" than anything else.
 * Hana to Akuma takes the Judeo-Christian version of demons, and tosses them in a blender with Western vampires and shapeshifters. Their king's named Lucifer, they consider fresh human blood a delicacy, and can alter their physical forms with a little magical aid.
 * Yu Yu Hakusho by a landslide. Hell, most of the demons in that show are different from traditional Japanese demons.
 * Inuyasha is a classic example of youkai that are translated as "demons," even though they don't have to be evil.
 * The oni suffer this too, despite that youkai and oni are completely different classifications. Although some oni had the misfortune of being called "ogre" instead.
 * Ushio and Tora is much the same as YYH and IY in the sheer variety, although traditional Japanese youkai tend to feature.
 * In Berserk, the Apostles, as demons are called in the series, are horrific beings straight out of nightmare. They can take human form, but always have a "tell" that serves to mark them as anything but. Their true form can be humanoid (such as Zodd), but many (like Grunbeld with his dragon form) are decidedly not. They answer to the Godhand, the five demonic gods that rule the spirit realm, who in turn answer to, which rules the Abyss. Every Apostle is unique because every one of them (even the non-humanoid ones) Was Once a Man, including , and they became demons when they got their hands on a Behelit and then reached an emotional nadir where they would do anything to escape their situation, at which point the Behelit summons the Godhand, and they make an offer for the bearer to become a demon in exchange for the sacrifice of those the bearer most holds dear. Apostles always take a physical form, so they can be killed with weapons, though pretty much every Apostle is hard as hell to kill.
 * Chrono Crusade has demons that were called "akuma" in the original Japanese, and are based somewhat on the Judeo-Christian, European tradition. ...Kinda. They have horns which draw in spiritual energy to fuel their powers (like regeneration), and many of them are somewhat humanoid, but their forms typically vary--there's a Catgirl demon, the relatively human title character, some demons that appear more like insect monsters...oh, and they appear to be in control of strange technology. In the anime, it's somewhat implied that they are corrupted, fallen angels, but in the manga
 * In Mahou Sensei Negima demons seem to just be powerful creatures that people summon to do stuff for them, generally killing so far. Demons themselves seem to be along the lines of a Punch Clock Villain and display no animosity, are pretty cheery when saying goodbye and are rather casual. Then again, they don't seem to mind the whole killing innocent people thing much, either.
 * The Magic World shows us some demons who have their own free will, and they're shown to be... well, mostly like other humans and humanoids really, except with horns and other demonic features. Some are good, some are bad, some work as announcers, and some work as bounty hunters who lament the fact that their fearsome appearance means the scary fights are mostly dumped on them.
 * It's also apparently possible to become a demon by
 * The demons of The World God Only Knows are natives of the Underworld, who appear near-indistinguishable from humans, apart from some odd quirks (strange dietary preferances, unusual hair colours, etc.), and have a minimum lifespan of several centuries. Later, it's revealed that these are the new demons; the old demons, their predecessors, found they could draw power from negative emotions, and corrupted living humans to strengthen themselves. The new demons revolted, overthrowing the old demons and setting up their own society.
 * The demons in Raideen are aliens, complete with cyborg monsters and robot mooks. It's implied that human legends of evil spirits were caused or influenced by previous wars with these creatures.
 * The demons in Devilman are ancient organisms who can fuse with other living things and inanimate objects to gain many abilities and powers from what they've fused with, taking them over completely. Thus they look like the chimerical creatures from ancient texts. They have psychic powers normally of varying strengths. However, human consciousness is lethal to them. But a person who's scared or otherwise loses control of their higher mental functions can be taken over. Should that person have a pure heart, however...they will posess the demon's flesh and gain their superpowers! And thus was born Devilman!
 * In Kyou Kara Maou the demons look exactly like humans, and are not inherently good or evil. They do, however, live five times as long as humans and have magical abilities.
 * In Naruto, there are nine super powerful demons that are differentiated by the number of tails they have (1-9). They have enormous amounts of raw power in the form of chakra that greatly surpasses any average human ninja in the series (though there are some exceptional shinobi, like Kisame Hoshigaki, whose power is said to be on equal levels with a tailed beast). These beasts are mindless since they are animalistic by nature, but when sealed within a person, their power can be utilized and put to use by the host's brain and intelligence.

Comic Books

 * Demons in The DCU speak in rhymes. Well, the higher positions of middle management do; one's position in Hell is partly signified by how well one can speak. The lowest ranks can't form language, the Lords of Hell speak clearly and fluently, and Hitman featured one demon several ranks below Etrigan who could only say, "I am Baytor!"
 * In The DCU Hell, a "lower" position is the better one. When Demons improve their standing in Hell, they fall even deeper into the pit. So a promotion is technically a bad thing. Neron was "promoted" to Rhymer after he screwed up big time..
 * Raven of Teen Titans is half-demon/half-human who must control her emotions lest her demonic side be set free.
 * Mike Mignolia's Hellboy, equipped with fire-engine red skin, cloven hooves for feet, and a right hand which can summon the Apocalypse. Oh, and immense horns on his head that need to be sanded down on a regular basis. In spite of his origins, he's one of the good guys.
 * We get to see more demons as the series goes on. Some, such as Astaroth, Ualac & Helldad fall into the same horned humanoid mold as HB, while others seem to be a twisted combination ov various human & animal parts. One storyline in BPRD features a demoness whose true form has the head of a crow, the wings of a bat, tentacles & an udder with dozens of human-like breasts hanging off it.
 * Part of this variation is because the different artistic styles of Mike Mignola and Guy Davis (the main artist of BPRD). While Mignola's demons and various monsters tend to be based more directly on real life animals, Davis tends to have a more Body Horror feel to his work. In one of Davis's sketchbooks he even comments that he had to tone down some of the "tentacles and Lovecraftian bits" for one of his demons before the comic went to print.
 * Marvel Comics' Anti-Hero Son of Satan is, as the name implies, the Half-Human Hybrid son of a very powerful demon who claimed to be The Devil. Of course, Marvel later backpedaled on the whole "real, honest-to-badness Biblical Satan" issue, and which of the many powerful Marvel demons it actually is has been Retconned several times.
 * For that matter, the very nature of demons in the Marvel Universe seems to be a matter of some contention; fallen or degenerated Physical Gods, leftover magical energy from the early days of life on Earth, holdovers from the Creation of the Universe... And of course, the fact that all of them lie their horns off all the time makes it no clearer.
 * Demons in Necrophim are strange-looking humanoid beings who resent having to share Hell with the Necrophim, and want the angels to finish what they started with Lucifer.
 * Devils in Harvey Comics (ie: Hot Stuff) aren't really evil. Like ghosts, they love playing tricks, but don't mean to cause any lasting harm.
 * The Hellspawn from the series Spawn are humans who made a deal with Malbolgia, the ruler of the eighth realm of Hell, to return to earth for either love or vengeance. Such people usually get sent back several years to a decade after their original death. They're infused with dark energy matter known as Necroplasm, which they have a limited supply of outside of Hell, and are bonded with a symbiotic armor that acts to protect its host. Hellspawn have inhuman strength, speed, movement and healing, and have the ability to use necro-magic (supernatural powers including teleportation, phasing, resurrecting the dead, necro-energy blasts, and much more). In addition, Hellspawn are able to "feed" off the evil energy of the world including people and "dark animals" (rats, bats, roaches, worms, insects, wolves, and snakes), and are also empathic beings able to sense the emotions of others whenever they choose. Finally, they can manipulate the elements and fly. A Hellspawn's time on earth is limited, and every time he uses his necro-magic, it brings the spawn closer to a second death and a return to Hell. The Hellspawn's job is to supply Hell with souls for its army by killing people with his energy, either innocent or evil.
 * The true demons of the Spawn universe are even more powerful than the Hellspawn. Violator, the main demon that the main character deals with, is superhumanly strong and resilient and has various supernatural powers including shape and size shifting, healing, Telepathy, possession of others, the ability to breathe fire, teleportation, and Necromancy.
 * Divangelic from Empowered is a pair of Conjoined Twins - her right half, Vanity, is a devil, but her left half, Charity, is an angel. The mind boggles...

Literature

 * In Piers Anthony's Xanth series, there are traditional "minor" demons (tempt humans, collect souls, horns, tails, etc.) and the Greater Demon X(A/N)^TH, a vast cosmic being who powers the entirety of Xanth's magic.
 * The smaller demons are also not necessarily evil (though they usually lack souls). Males tend to be big bullies, although some like Beauregard can get along fine with mortals. Females tend to be more naughtily sexy than malevolent. And all bets are off should any of them receive all or part of a soul: it tends to make evil monsters into good guys. As for the big, cosmically powered ones, they are also not evil, although they basically view mortal creatures as insignificant ants, and use them as the pieces in their big universal chess game.
 * The title character of Isaac Asimov's "Azazel" series of short stories is just out to help people... but his poor understanding of humanity and rather incompetent human intermediary tend to cause it to fail hilariously. Though he may actually just be a Sufficiently Advanced Alien. Also, he's only two centimeters tall. And the Unreliable Narrator may be making him up.
 * In the Myth Adventures series by the late Robert Asprin, "demon" is just a corrupted form of "dimension traveler", meaning that the term takes in a wide variety of species - and that humans who travel to another dimension are also regarded as "demons" there. Some demons look the part, like the horned, red-skinned, goat-legged Deveels, but even they're just avaricious Space Jews.
 * More like Space Arabs.
 * In R. Scott Bakker's Second Apocalypse, demons are summoned by Functional Magic from the Outside. The cost is that after the summoner dies, the demon will torture him forever as a payment for having been forced to submit to another's will. Some people don't think the cost that high in a world where sorcerers are considered damned anyway.
 * In Jim Butcher's The Dresden Files (particularly Death Masks and Small Favor), the Knights of the Blackened Denarius are human hosts to fallen angels. Each host, after an initial temptation, took up one of the thirty titular denarii (the thirty pieces of silver given to Judas for betraying Christ). Each of the Fallen lives within its human host, who grants him or her various abilities such as Voluntary Shapeshifting. If a host is killed, the coin he or she holds comes out of the corpse, which reverts to human form, and attempts to catch another host.
 * They are specifically known as the Fallen though. "Demon" is a generic term for any being from a specific region in the Nevernever.
 * In addition, there are a variety of super-demons known as Outsiders that come from beyond the Nevernever. These are considered so horrible and dangerous that any wizard who summons one (or even seeks one out) is sentenced to death
 * The demons in Steven Erikson's Malazan Book of the Fallen are any type of alien creature from an Another Dimension. There are many different kinds; the only commonality is that they can be summoned and controlled by sorcerers or alternatively bargained with. As a consequence, some of the demons seen in action are gentle souls who just want to go home to their old life as a humble extradimensional peasant.
 * In Kim Harrison's The Hollows, demons are not mythological beings but a powerful race of Black Magic using Shape Shifter Aliens living in the novelâ€™s Alternate Universe Dark World the Ever After. They can be summoned to make a Deal with the Devil for things such as magical knowledge, assassination or in one case giving legal testimony. Demons often attempt to manipulate the deal in order to take the summoner into the Ever After and enslave them as a Familiar which is considered A Fate Worse Than Death.
 * Douglas Hill's young-adult novels Blade of the Poisoner and Master of Fiends featured demons that resembled everything from giant vultures to grotesque crystalline golems to Eldritch Abominations. They were all hard to kill to some degree or another, and all uniformly nasty.
 * CS Lewis' The Screwtape Letters is an exploration of what sort of society demons might have. The demons' physical form is not described (though when Screwtape gets particularly infuriated he becomes a large centipede, requiring him to fetch a secretary to take dictation), but Hell is sort of like a Police State full of Corrupt Corporate Executives - ordered under Satan, but still squabbling and infighting amongst themselves.
 * In the Colt Regan universe, Demon is a sort of catchall term for various types of extraplanar beings with whose traits vary wildly from type to type. Often containing one (or more than one) of the common traits listed above.
 * Nasuverse demons are rather unique in that they are described as an actual 'substance' in and of themselves. Unlike other phantasm creatures (eg. unicorns), they are created from the images of humanity and exist only to draw in disruptions. Possessions are actually the demons' attempts to draw pain and suffering away, but being 'impossible' creatures, their manifestation generally causes harm and eventually kills the host.
 * Then you have all the cultural variants which may also be labeled as demons but are completely different, like the oni in South-Asian countries.
 * In the Incarnations of Immortality series, Demons can be created out of "ether" by the Incarnation of Evil and can look like pretty much anything he wants them to.
 * In Stationery Voyagers, they're of the Fallen Angel variety. Their main function is to undermine the Minshan faith whenever and wherever they can, so as to sour Minshus' victory over them in the Web of Destiny. Their secondary function is to aid any Evil Sorcerer they can find and to aid the Drismabons in their quest to make the universe implode. They rarely assume physical form, preferring instead to manifest as whispers of doubt that plant destructive ideas in the susceptible on both a conscious and subconscious level. When they do materialize, they often look like a cross between Ty fighters and Decepticons. The Dark Wanderer, Lord of all Witchcraft, wears a black-and-red combat gear suit nearly identical to that worn by the good angels. While both good and evil angels can sometimes seem to be acting like jerks around humans, good angels are usually The Stoic full of Tranquil Fury whereas evil ones behave more like a Large Ham.
 * Demons in Good Omens are of the typical biblical Fallen Angel fare, with the exception that their wings don't really change -- they just keep them better groomed.
 * In The Descent by Jeff Long, it turns out that there is a physical, real-life equivalent to Hell and demons - an underground world of tunnels and the brutish "hadals" that inhabit it. These creatures are degenerate hominids with demonic features and a taste for senseless, incredibly brutal violence. They are also led by a kind of Satan.
 * Middle-Earth demons are Ainur (angels) who joined Morgoth in rebellion against Eru Ilúvatar. Being shapeshifting spirits with various areas of influence, they come in several types, ranging from relatively weak vampires and werewolves to the immensely powerful Balrogs (and possibly Dragons too), and Sauron who seems to be (mercifully) unique in sheer power level.
 * Despite "orc" deriving from an old word for demon, Tolkien's orcs are not demons of any kind (though it's implied that some of their commanders were orc-shaped demons) -- rather, they were mortal creatures likely bred from Elvish and/or human stock. Real demons are far more powerful.
 * There are also rather odd beings of uncertain origin, like Ungoliant, a bizarre spider-monster whose nature is never explained. As all the evil in Arda was caused by Morgoth, she might even have come from somewhere else. Then there are the frightful, "nameless things" that "gnaw" the roots of the Earth, mentioned but never described by Gandalf.
 * There are two kinds of demons in the Night Huntress books, those in their own corporeal bodies and those possessing hapless victims. A possessor cannot be killed, as they simply jump away into the nearest living thing when their current host dies. Corporeal demons are vulnerable to salt and cannot cross thresholds without an invitation.
 * In Black Dogs, demons are incomprehensible creatures stretching out into unknown dimensions, able to be summoned and controlled by uttering their names.
 * In The Guardians, demons are Fallen Angels who followed Lucifer in his bid for God's power. They are bound by Rules not to harm humans or deny their free will, but they can still tempt them with bargains and wagers.
 * In Quantum Gravity, demons live on another plane of existence, and Hell is not a physical place. Devils are best described as evil spirits, and are basically the opposite of everything that demons stand for. Demons make everything an art--you might not want to think too hard about that--and are very much for being one's self, regardless of what that is. Devil's push people to make sacrifices (of self) now for some vague reward in the future, e.g. the greater good, prestige. A demon with (a) devil(s) cannot behave a a demon, and becomes an imp; imps push people through/around Hell. Demons come in many colors, and every shade means something different. Humans cannot become demons, but any creature who can interact aetherically can., for instance, is born but is also a demon.
 * The Demons (or, if you're a Morindim, the Devil-Spirits) in David Eddings' The Belgariad and The Malloreon, are incredibley powerful beings who can be summoned by the truly reckless (or the truly stupid) to do their bidding; practionioners of this are known as magicians or wizards. The smarter magicians bind their Demons inside an illusion and protect themselves with pentagrams and other magical protections; as long as the Demon remains inside the illusion, it must do it's master's bidding, if and when it breaks out, the pentagram will (hopefully) protect it's master. The stupidest magicians just summon the Demon and try to force it into doing their bidding. They seem to come in an infinite number of forms, and have a wide variety of powers from the application of sheer brute force, to More Than Mind Control, and full on Demonic Possession (of a freakin' dragon, no less). They seemingly cannot be killed, and must be sent back to their own universe; this is a pain for the heroes, especially once two contenders for the role of Big Bad start using a pair of Demon Lords as their respective Dragons; unlike normal Demons the Demon Lords are consenting to work for their masters, largely to fullfill their own agendas. Hell, their home base, is alternately described as another universe, and a "state of mind"; they are said to work for a Satanic figure known only as "The King of Hell," who seeks to become ruler of the universe. It's worth noting that summoning a Demon never ends well; eventually it gets away and either eats you, or (in the case of the two Demon Lords) drags your soul into Hell and feeds upon it for the rest of eternity.
 * Terry Brooks' Shannara series has two kinds: the genuine Demons, who are evil Faerie creatures, sealed up beyond the Forbidding by the good Fae, and the "demons" of Morrowindl, who are really just . And then there's the Jachyras: evil Faerie lunatics so mad that even the Demons thought they needed sealing.
 * His series The Word and The Void has another kind: former humans who, having sold their souls, serve The Void for all of eternity. They have a wide range of powers, including Shapeshifting, mind control, spellcasting, or just plain blending in, and seek to reduce all of creation to raw chaos.
 * And the Magic Kingdom of Landover provides the demons of Abbadon: exiled faerie beings who want back into the mists and are more than willing to go through Landover to do it.
 * In L. Jagi Lamplighter's Prospero's Daughter, demons are a major element and have been in the Backstory; one of Prospero's son is nicknamed Demonslayer.
 * In Sara Douglass' The Crucible trilogy demons are the offspring of angels and mortal women who are consigned to Hell to keep them out of their fathers hair and because the angels consider procreation shameful although some have avoided this fate and seek to overthrow their fathers rule of Earth.
 * The negative implications of demons are completely averted in the Dragaera series, which has a lot of Dark Is Not Evil present, as the term term only means "someone who can be summoned" without any moral implications. Verra the Demon Goddess (the patron goddess of some of the protagonists and the mother of one of them) is called as such because she was formerly a slave to the Jenoine before taking her position. There's also a character called the Necromancer who is an undead demon summoned from a place called the World of Seven Doors, who thereafter serves Sethra Lavode and aids the protagonists. This probably also explains why a gangster in the series is known as the Demon- he's an assassin and can be "summoned" for the right price.
 * in Kage Baker's Children of the Sun series demons are actually air elemental (Their name for themselves is "Children of the Air"). Not necessarily evil but very chaotic they have a natural form which can only be seen by those with magical sight but they can assume (or be forced into by a magician) a physical form. if it's a chosen form then they can also dissolve it and their next physical form can be totally different. if forced magically into a form they are stuck in it until released or killed. if their owner has their true name then they can be returned to that form. If not then they are free.
 * The Age of Fire series has demen ("deep men") - horned, dorsal-spiked, carnivorous hominids who inhabit the more inhospitable parts of the Lower World. They're not really demons per se, but the similarities are probably intentional.
 * In the Riftwar Cycle, there are seven known levels of existence, with each being more dangerous than the one above it. Mortals come from the first level; demons are from the fourth and fifth (the overwhelming majority of demons featured in the series are from the latter). They are characterized by being incredibly vicious and living only for the id, and possess the power to absorb traits and knowledge from other living things they eat; there are several different "paths" a demon's evolution can take as it aborbs more powers, though they all seem to start out as imp-like beings, and will eventually reincarnate if killed. They are ruled in their own realms by Demon Kings, the most notable of whom are Maarg and Dahun, but can be summoned by sorcerers to the mortal realm (weaker demons are much easier to summon and compel- incredibly elaborate preparations are needed for an attempt to summon Dahun, and no attempt is even made to try and control him). A Kingdom Besieged had a young demon named Child as a major POV character.
 * Fantastic Beasts and Where to Find Them describes some magical beasts as demons. All they have in common is that they're small, vaguely malevolent, and rather pathetic.
 * In Fred Saberhagen's Empire of the East and Books of Swords universe, demons are powerful evil spirits who used to be nuclear bombs. When a general global nuclear war broke out, the United States activated a device called Ardneh that literally changed the laws of nature within the vicinity of planet earth to make nuclear reactions much less likely, preventing the chain reactions that make nuclear bombs, and nuclear reactors, possible. While this saved the human race, it also led to the collapse of technological civilization, and made magic possible and real. In this new, magical, world, the nuclear bombs became the demons. Fortunately, Ardneh still lived to fight them.
 * In Roger Zelazny's Book of Amber series, "demons" is the term used to refer to all of the creatures that inhabit the Courts of Chaos, other than the Lords of Chaos themselves (a distinction which gets a bit blurry at times). Some look like the traditional horned and scaly monsters, but they run the gamut from talking cats to mathematical abstractions (they are creatures of Chaos, after all). The one thing they all have in common in that they are all capable of Voluntary Shapeshifting to one degree or another. This is not so much a magical power as it is an evolved survival mechanism for living in Chaos, where the environment is frequently subject to change without notice.
 * The Bookof All Hours - the Unkin.  In the multiverse inscribed on the surface of the Vellum, these meta-humans have long since taken up different roles, presenting themselves to mortal humans in different ways in pursuit of power.
 * In the web-novel Domina, demons are just humans who used the toy maker to add horns, fangs, and maybe a tail to their bodies. Although there are the succubi...
 * Sandman Slim has Hellions, which are the traditional fallen angels, and demons, which are more elemental-esque beings of hunger and evil.
 * Felix Castor has demons of many stripes, ranging from the old standards (Asmodeus, Moloch, succubi like Juliet) to more mindless, rampaging things (The Naming of the Beasts sees something Juliet compares to a herd animal of Hell possessing a gymnasium). Like ghosts, they can be called up and exorcised by any number of means.
 * Felix Castor has demons of many stripes, ranging from the old standards (Asmodeus, Moloch, succubi like Juliet) to more mindless, rampaging things (The Naming of the Beasts sees something Juliet compares to a herd animal of Hell possessing a gymnasium). Like ghosts, they can be called up and exorcised by any number of means.

Live Action TV

 * Despite Buffy the Vampire Slayer and Angel ostensibly taking place in the same universe, demons had a drastically different role in the two series, and indeed this meant that by the end of it things shifted drastically. In early Buffy, demons are Always Chaotic Evil - always - while representing the fears and traumas of high school teenagers. In early Angel, demons represent the downtrodden. Sometimes. Except when they're Always Chaotic Evil. By the end of things, it was pretty confusing.
 * This is justified arguably by the fact that all living demons are actually hybrids, so while some might be Always Chaotic Evil, others might just be chaotic neutral. The only true demon we ever see is.
 * Well, there's also the "top surface" demon coming out of the Hellmouth in the season 1 finale and in "The Zeppo". We never see the whole thing, though.
 * It may be that more of the demons in Buffy were Always Chaotic Evil than in Angel because Buffy takes place in Sunnydale, a town built on top of a Hellmouth and specifically founded to be a feeding ground for demons, while Angel takes place in Los Angeles, which has a greater diversity in the evil to demon ratio.
 * The Scourge claim to be pure blooded, supported by the fact that a machine designed to kill anyone with human blood didn't affect them. Adding a bit of complexity to the True Demon dynamic.
 * We do get to meet one of the Old Ones (Illyria), but only after she . Her true form is only shown in an illustration.
 * Given that Buffy's demons and magic are frequently a metaphor for growing up, the demons going from appearing as Always Chaotic Evil to being more varied in their portrayals could simply be a metaphor for the realization that life is not always as black and white as we think it is when we're young.
 * Case in point, Clem. Appearing in seasons six and seven, he's a nice guy, with the exception of liking kittens.
 * Truth be told, a lot of demons in later Buffy episodes seem to be more Always Chaotic Neutral or Always True Neutral. Take Anya's vengeance demons for example. They're not explicitly malicious, and in many ways act like bureaucrats of the demon world. They have hopes and dreams and desires, and if it means they have to make a man's penis explode in the course of their jobs, so be it. Most of Anya's relatives at her wedding are actually quite friendly, and only turn on people once Xander's dad starts acting like a complete asshole. Really, like in Angel, the implication seems to be that demons just have different standards of goodness than humans do.
 * There are several instances where Angel kills a horrible looking demon monster only to learn that he was actually on the side of good, and assuming him to be the enemy. There are guardian demons, protector demons, empath demons, healer demons...Most look quite monstrous regardless of their profession.
 * In Supernatural, the demons, both the low-level ones and the high-level ones like Azazel, Lilith, and Alistair, are human souls that have been twisted by Hell's torments. Lilith being the very first human soul Lucifer corrupted.
 * Reaper's demons have horns and can shapeshift, but mostly look and behave a lot like normal humans.
 * Some of them even want to bring down the devil for non-selfish reasons. By planting flowers. Don't knock it, it probably would have worked in about 400 years or so.
 * Charmed uses demons as the main antagonists for most of the series. Generally, the term "demon" is used for any magical person or creature who uses their powers for evil. Initially, many demons had odd, otherworldly appearances, and some also came in more human-looking varieties, but budget-cuts in later seasons led to ALL demons basically looking like humans with a penchant for leather.
 * At times, warlocks are also treated as low-level demons.
 * 'Lost Tapes'', despite being about mysterious animals, has a few supernatural demons appear in it. Mainly, the Hellhound and the Jersey Devil. It also features the "Dover Demon"--no one knows what the hell that one was.
 * At times, warlocks are also treated as low-level demons.
 * 'Lost Tapes'', despite being about mysterious animals, has a few supernatural demons appear in it. Mainly, the Hellhound and the Jersey Devil. It also features the "Dover Demon"--no one knows what the hell that one was.

Music

 * The Boogieman (Sun Moon Stars). Looks like this.

Mythology and Folklore

 * In the Old Testament, demons like Beelzebub, Lord of the Flies, were the gods of other tribes in the near East. Beelzebub was a corrupted form of Ba'alzebul, or translated from Phoenician, "Lord of the Temple". Zebub means "flies" in Hebrew, so it was a kind of a Take That to old Baal.
 * Didn't help that at least one Baal (there were a bunch of them) had a habit of divination by watching flies. (hey, the Romans did it with birds...)
 * In Slavic mythology word Demon is used to refer ANY kind of supernatural creature, wich is not God.
 * The English word Demon comes from the Greek Daimon (Latinized to Daemon), but in pre-Christian Greek Mythology the meaning was quite different. A Daimon is a spirit or minor deity that lurks in the background doing minor things gods don't want to bother with, or personifying concepts like Death, Sleep, Famine, Insanity, Piety, and Hope. Generally Kakodaimones were the bad ones, and Agathodaimones were the good ones. Daimon was also used for a sort of personal guardian "fate" or soul-double that accompanied a mortal through life.

Tabletop Games

 * Word of God says that the Mortasheen equivalent to demons are The Devilbirds, birds that have been psychically charged with certain emotions and must eat said emotions for sustenance, tending to do it in the most horrifying ways possible. Yeah, it's that kinda series
 * Dungeons and Dragons has always maintained differences in Devils, Demons, and Daemons. Mostly. There have also been numerous minor fiendish creatures, such as Rakshasas, Oni, Barghests, Demodands/Gehreleths, and so on.
 * In the original edition of D&D, there were only Demons, with no Devils. The most powerful type of Demon was the mighty Balrog (which became the Balor after the Tolkien estate complained).
 * In the first edition of Advanced Dungeons & Dragons, Devils are Lawful Evil and come from Hell, Demons are Chaotic Evil and come from the Abyss, and Daemons are Neutral Evil and come from Hades. They were given little to differentiate each other aside from how Character Alignment defined their behavior.
 * In the second edition, due to controversy about being Satanic, the terms Demon, Devil, and Daemon were banned from the game and renamed "Fiends", which were separated into the Lawful Evil, corrupting, tyrannical Baatezeu (Devils) from Baator; the Chaotic Evil, monstrous, bloodthirsty Tanar'ri (demons) from the Abyss; and the Neutral Evil Yugoloths (Daemons) from the Gray Waste, who are extremely manipulative and expert liars. The Planescape campaign setting introduced the Blood War, an eternal conflict between the Baatezu and Tanar'ri, with the Yugoloths serving as mercenaries for both sides.
 * Third edition restored the names Demon and Devil, but otherwise changed little about their role in the game. They also retained the Yugoloths (but did not go back to calling them Daemons), but downplayed them. The Blood War was still going.
 * Fourth Edition finally broke the tie between the two Devil and Demon categories in nearly all aspects:
 * Demons are brutish, chaotic, and mindless monsters from the Elemental Chaos (specifically, the Infinite Layers of the Abyss) who just rampage constantly and are utterly inhuman in a number of ways, including appearance. Most of them are either chronic backstabbers or destructive horrors who wish only death and war.
 * Devils resemble the more "traditional" Faustian demons; are the fallen servitors of a god who murdered another god, seductive corruptors who tempt mortals with promises of power in order to collect souls to increase their power base and grow in their incredibly bureaucratic and back-stabbing society, and most of them are very humanoid and fairly attractive. They make their home in the Nine Hells of Baator, located somewhere on the Astral Sea.
 * Because Neutral Evil is no longer an alignment in fourth edition, Daemons/Yugoloths have been turned into Demons, but are Evil like Devils, so they fulfill the machinations of the Abyss.
 * In Eberron, Demons and Devils are not a huge part of the setting. The concept of the dimension-spanning Blood War is limited to a single plane, Shavarath, where the Demons, Devils, and Angels are all locked in constant combat. Yugoloths still presumably exist in Eberron's cosmology but are given little attention. The more important fiends are the Rakshasas, who are actually native inhabitants of the world rather than extraplanar beings, and they ruled the planet for millions of years before being ousted from power by the dragons.
 * In Ravenloft, Demons (and fiends in general) are rare and mysterious beings, which enter the setting by transposing their bodies with those of morally corrupted human beings. Once in the Land of Mists, they are unable to return home; many acquire additional powers by performing rituals in various domains. Demons are able to cross sealed domain borders freely, as their vast evil cancels out the influence of darklords in a small area around them.
 * Pathfinder follows the example set by 2nd and 3rd Edition D&D, minus the Blood War. It defines the actions of the three fiendish races by their motivations: Devils want to corrupt the minds of mortals, Demons want to corrupt the body, and Daemons simply want to kill. Devils want dominion, Demons want destruction, and Daemons want oblivion.
 * In Dragonlance, Demons, Devils, and Daemons exist, but they are all subservient to the gods of evil. Since the evil gods seem to prefer using their mortal servants to carry out any tasks they want done, the three fiendish races are rarely seen.
 * In Infernum, a D20 setting, demons are biological weapons created by Fallen Angels by crossbreeding themselves with Spawn (sort of mindless, soulless, proto-type lifeforms), then established into the nine Breeds (Artificer, Beast, Deceiver, Fiend, Hulk, Imp, Malcubus, Stalker, Slaver) by a long regime of surgery, crossbreeding, incest and black magic. Realising they were expendable in the eyes of their "fathers" they rebelled, ate all of them they could catch, chased the others clear out of hell, then took the place over. They torture souls to extract a substance called 'iliaster', which is literally meat, drink and fuel to them. And these are your player characters. Oh, and there's no real difference between 'demon', 'devil' and 'daemon' -- those names are actually social ranks, listed in ascending rank.
 * The RPG In Nomine has an incredible assortment of demons. All they have in common is that they're Fallen Angels, and every demon is a perverted version of the angel they used to be. The exceptions are the Lilim, who are all the children of Lilith and were never angels.
 * Exalted:
 * All true demons are a type of spirit that is a part of a Yozi -- Eldritch Abominations / dethroned Creators of the Universe. Each of the 23 Yozis has multiple souls with minds and wills of their own -- at least 12, but the most powerful among them, Malfeas the Demon City, has 23. These are called Third Circle Demons. In turn, each Third Circle Demon itself has seven souls, these are called Second Circle Demons. The Second Circle Demons can create new species of demons, which are known as First Circle Demons. The First Circle demons can range from 24 fingered harpists who use time as a harp to beetles that swim through flesh and eat poison. Oh, and shape-shifting prostitutes are in there as well (they don't want your soul either, just some flesh to make a baby with way too many parents). Oh, and the major religion of the setting considers summoning them OK as long as you know what you're doing (and are a Dragon-Blooded, mortals shouldn't reach above their station, which is genuinely good advice on demon summoning in game).
 * And then there are the Infernal Exalted, who come from Solar Exalted shards warped by the aforementioned Yozis. While the Infernals start out as humans given great power with a few demonic touches and a First Circle demon's voice in their heads, they ultimately develop into something closer to a Yozi than a human. And they don't have to stay under their Yozi patron's control, either.
 * In Warhammer and Warhammer 40000 daemons are created by the Chaos Gods, who themselves are the personifications of mortal emotions in the Warp. In Warhammer the Realm of Chaos is effectively Hell, but its 40k counterpart does a few things differently.
 * The Warp in Warhammer 40000 is the source of all Psychic Powers in the setting, functions as the universe's "Hyperspace", and is where mortal souls go after death. The Warp is made of "psychic energy" affected by, and possibly created from, the emotions of sentient life. Eventually, particularly strong emotions gave birth to the aforementioned Chaos Gods, along with lesser daemons who act as extensions of their corresponding god's will. Daemons of a particular god will represent various aspects of its patron.
 * Thankfully, daemons are unstable in the Materium, and must pass through a Warp rift, be summoned via ritual, or find a host. Once they have crossed into our plane of existence, however, daemons are extremely dangerous, as they tend to be empowered by literal gods or warp reality around them. The trouble is that any psyker that has not been discovered and trained to control his abilities is susceptible to sudden, involuntary Demonic Possession.
 * Finally, one more way these daemons are different, is that as purely psychic beings they are extremely vulnerable to anti-psychic weaponry and cannot even touch blanks. This has allowed some factions to develop a few specialized anti-daemon countermeasures. Such weapons are rare, however, and More Dakka is often sufficient to kill Lesser Daemons. Of course, when all else fails, there's always Exterminatus.
 * The demons of Demon: The Fallen are angels who were stripped of corporeal form and cast into the Abyss; a recent clusterfuck in the spirit world freed most of them, though some of them were summoned to Earth by mortal sorcerers, bound to inanimate objects, and eventually became Eldritch Abominations. A demon typically needs a soulless body (e.g., someone who's brain dead, a severely catatonic mental patient, a recent murder or suicide) to retain a presence on Earth; strangely, this is actually a humanizing experience for many demons, as they get to experience what humanity's like after millennia of abuse. They still retain many of the powers they had as angels (which range from controlling flame to reshaping flesh to overseeing the dead), but can willingly tinge these powers with "Torment," which makes them more destructive and more likely to screw with humans.
 * In World of Darkness: Inferno (the New World of Darkness take on the subject), demons are embodiments of sin, looking to spread the sin they identify with on Earth to increase their power. Some demons can possess humans, giving them access to special abilities deriving from their iconic sin, both literally and thematically. Demons dwell in Hell, a realm of sin incarnate. The ultimate origin of demons is unknown; some demons are ghosts and spirits who fell to corruption, but not all.
 * Demons in Magic: The Gathering are generally somewhat expensive to summon, powerful, and potentially a hazard to their summoner. (A classic example is the Lord of the Pit, which basically turns on its controller if not regularly fed other creatures.) Most of them fall into the purview of black on the game's color wheel.
 * There isn't that much fluff as to where they come from, except in Kamigawa block, where Oni are a particularly evil type of demons that make deals with ogres. Kamigawa is one of the few blocks to have demons without a trace of black mana in them - there are two oni that are mono-red.
 * Outside Kamigawa, most demons are the bat-winged, clawed, fanged, gigantic monster kind. However, one early demon was the flightless, half-fungus Mold Demon.
 * In Innistrad, demons cannot be truly destroyed, only sealed away, and their inhuman desires and urges take physical form as little devils that spawn from them and wreak havoc.
 * Griselbrand finds out that.
 * There's also the Red aligned devils, which are essencially internet trolls with far more means to do damage. In an inversion of the Dungeons and Dragons system, Demons are Lawful Evil or Neutral Evil, while devils are Chaotic Evil.
 * Gamma World demons are an incredibly recent addition (As in, this current edition is the first to have them) to the game, basically being other-dimensional beings that can only appear in the world with the right mathematical equations. Some of the demons include a Creepy Child, a Sinister Minister, a demonic police officer that is an obvious homage to O Brother, Where Art Thou?, and a gigantic Poisonous Demon.
 * Demons in Reign -- although exceptionally powerful magical beings -- are of decidedly natural origin, hatching from eggs that form in the earth of the game world. They also get really freaky as they get more powerful, to the point that the most powerful can usually break off parts of themselves to act as independent agents, and are statted with the system the game uses for kingdoms and organizations, rather than characters. Also, since they hatch from eggs in the ground, the world's giant fleas made of earthen materials which suck minerals out of the earth tend to be full of them.
 * Fiends (Demons in Japan), in Yu-Gi-Oh!, have their own type, and go all over the place as a result. Almost all of them are DARK, and they vary from (often lethal) Joke Characters (Kuriboh), to chess-based Legions of Hell (Archfiend), to Demonic Invaders from Another Dimension (Dark World), to Horny Devils (Yubel) to Evil Counterparts (Evil Heroes), to borderline Eldritch Abominations (Raviel, the Devil Gods, Darkness Neosphere). It's sort of a catch-all category for things that could potentially be viewed as evil and aren't The Undead, in which case they're Zombies (well, Undead in Japan) Alien Invaders, which are almost always Reptiles for whatever reason, or Knight Templar, in which case they're usually Fairies (Angels in Japan).
 * Nobilis features both Devils and Demons. Devils are Fallen Angels (the motive for their Fall differs between edition: in first and second editions, they held corruption to be the highest principle, the foundation of existence, while in third edition, they fell because they believed everything, no matter how evil, deserved love); Demons are the beings who have populated Hell since before Lucifer's Rebellion, and are on a much smaller (spiritual) scale.

Video Games

 * Doom's monsters are invaders from Hell. They either take a monstrous physical form or they possess humans who become zombies, and some of them, such as the Cyberdemon, the Spider Mastermind, and the Mancubi, have cybernetic enhancements. Mainly the only way you can kill these things is with lots and lots of firepower, with rockets and energy weapons being used against the most powerful ones. In Doom 3, you have to use a magical weapon called the Soul Cube to take down the biggest and baddest one of them all. Likewise, in Doom 3: Resurrection of Evil, you have to use The Artifact, a weapon created by Hell itself, to kill off the guy who started it all. Oh, and he turned into a skeleton-dragon. Oh, and at the end, it makes you invincible, incredibly fast, and causes you to turn hell knights into Ludicrous Gibs with your bare hands.
 * The Daedra of The Elder Scrolls series are immortal entities from the realms of Oblivion, and the closest thing to Demons in Elder Scrolls lore. The Dremora, a specific race of Daedra, are the closest thing (aesthetically, at least) to traditional Demons. It is even Lampshaded in an in-game book that the word "Demon" is simply a mistranslation of "Dremora" that became popular with the general populace before anyone could correct it.
 * Also, many are pretty friendly, although it depends upon the Daedra Prince. Some are princes of Destruction, or Rape, for example (the habitation and minions of the former were portrayed, in Oblivion, as looking pretty much like a standard-issue hell) and then there are princes of dawn and dusk, madness, dreams, and so on. Also, because they are immortal, they have completely different concepts of good and evil. So Mehrunes Dagon (the equivalent satan more or less) cant be seen as really evil, since his reasons for the Oblivion invasion could be far too hard for mortals to understand.
 * It might be better to think of the Daedra as a whole as differently moral... being quite immortal, the actions and fates of mortals are of fleeing interest. Summoned by a mortal wizard and forced to do his bidding? Being bound into a magical sword for a thousand years? When you can exist for millions, its of no more irritation than a human might experience with a few weeks in jail.
 * In the Warcraft universe, certain demons were natural species that were corrupted by more powerful demons, most notably the eredar.
 * Thanks to the Burning Crusade Expansion Pack, the lore currently has it that the eredar themselves were corrupted by an insane divinity. Except some of them got away.
 * The demons that weren't originally mortals were created in the Twisting Nether (a chaotic plane of existance that is the source of magic and apparently where the souls of the dead go).
 * Sparda in Devil May Cry seems to be some sort of part-insect/part-goat humanoid thing. Also, Dante and Virgil are humanoid lizards in their devil forms, and just about every demon is completely different to each other.
 * Demons in Dwarf Fortress are physically an extremely varied lot - procedurally generated beasts (as are Titans and Forgotten Beasts), ranging from horrible amalgamations of mundane animals with uncanny features such as three eyes, composed of things like ash or snow or what have you (though immune to fire and temperature regardless), with terrible poisons that will do anything from causing mild itchiness to making your eyes rot - but they all fly and ALL want to rip you to pieces. Sometimes they hijack human civilisations by tricking the inhabitants into believing they're a god, or goblin civs by means of brute force.
 * Final Fantasy XI's demons are of the summoned-and-serve variety that serve the Shadowlord, although it seems they originated from
 * Disgaea demons are generally absurdly powerful pointy-eared humanoids with a penchant for Card Carrying Villainy and breaking the fourth wall. There are also "monster-type" demons that include anything from Beasts, The Undead, or Dragons, to Metallic monsters and Cat Girls.
 * In the Diablo setting, demons are psychotic hordes sometimes created or altered by their leaders, the Prime Evils and the Lesser Evils. Even though they seem to have free will, they still do the bidding of their particular masters without question. They come in a huge variety of forms -- from almost-human to green porcupines to The Blob to totally alien. In the second game, many enemies are not true demons, but creatures mutated by the forces of Hell.
 * In the first game as well - the undead are not demons but corpses animated by the power of the Prime Evils, and the weaker creatures like Scavengers are mutated once-natural animals.
 * In City of Heroes, demons are explicitly magical, and most commonly associated with the Circle Of Thorns (an evil cult/lost civilisation... it's complicated). Other demons include the Wailers, who make deals with wannabe musicians and attack with the power of sound, and the demons bound by Anti-Hero Infernal, and his Mirror Universe counterpart.
 * Infernal is a demon, or at least a half-demon, as well. His mother turns out to be Lillitu, the Succubus Queen.
 * And that's only the official demons in the game lore. Good luck trying to count all the types of demon and half-demon player characters running about.
 * Arcana Heart demons are pretty much like your traditional demons. You know, comes from hell, could get summoned with a ritual, has horns and wings and fangs... well, besides the fact that all the demons we've seen so far are generally good, cheerful sorts with the most evil one being the Jerk with a Heart of Gold Mike. Oh, they're considered so much of an Unusually Uninteresting Sight amongst humans that they can legally get married to human women and receive jobs in the corporate world while their obviously half-demon children (complete with little wings and fangs) go to school and become friends with the local Miko (who will nonetheless note to said friend that there are certain rules against demons threading on their shrine). There is even one that is a nun.
 * In Albion, demons are magical creatures deliberately created by wizards for use as living weapons by giving form to their fears. The list of fears they came up with for the game isn't very imaginative or sensible, as the only demons in the game are Fears, Animals, Plagues, and possibly Storms.
 * Demons in Dragon Age Origins are denizens of the Fade that long to experience mortal life and are defined by different emotions: Rage, Hunger, Sloth, Desire, and Pride. To this end they frequently attempt to possess mortals, mages being their ideal targets. (Mages are self-aware while visiting the Fade and a possessed mage becomes a new creature called an abomination.) Some of Anders' and Justice's dialogue in Awakening hints that any spirit of the Fade can become a demon if their desires become too strong. This is likely the reason Justice is both fascinated and disturbed by the love that his deceased host Kristoff and his widow Aura shared — the desire for such a thing could very well turn Justice into a demon.
 * This is demonstrated in Dragon Age II, where Ander's hatred of Templars has turned Justice into a demon of Vengeance. Anders can let Vengeance take control of him as a sustained ability; he will do more damage in this state, but can't be healed.
 * Demons in Lusternia are extraplanar entities that were corrupted by the effluence of an Eldritch Abomination, ruled over by a council of similarly corrupted Demon Lords. They come in four varieties: slimy, greedy little imps; androgynous, sex obsessed fiends; crimson skinned classic demons; and hulking, winged Archdemons. They can be trafficked with, but only by Nihilists.
 * Touhou Project can a be a bit complicated. To begin with, there are creatures called in the Japanese akuma which are translated as devil; additionally vampires are a type of devil. Oni may also be a type of devil; some are said to work in the Celestial Bureaucracy and others live in an abandoned hell underground. (Note that the Japanese word for vampire contains the character for oni; there may be an Incredibly Lame Pun going on). All of these have been referred to as types of Youkai (but clearly not all youkai are devils). It gets more complicated with the existence of Makai (literally Demon's World). It's apparently not hell, but it's said to be inhabited by demons in the translation (This troper does not know what the Japanese word used in the manual is), which may/may not be different from devils. It should be noted that Makai is ruled over by an obvious Satan analogue but she is in fact described as being a God, and having created the place.
 * In Primal the inhabitants of all worlds except for earth are called demons. Only the wraiths and djinns have a real tendency towards evil, and even among them there seem to be some people who are quite okay. The udine and ferai are actually rather nice people, and none of the demon races look in any way demonic.
 * In the Shin Megami Tensei franchise, "Demon" is actually a catch-all term for any supernatural being ranging from goblins and fairies to gods; even angels are technically one specific type of demon (though they'd probably be very angry at you if you called them that). Demons in general are still very bad news for unwary humans, despite not all being horned monstrosities straight out of a Doom game. This goes back to one of the original meanings of the word, simply "spiritual being." Technically the original word was "daemon", but close enough.
 * Might and Magic have had multiple types of demons and devils since the beginning of the series. The first were powerful hostile creatures with no apparent connection to the later ones in the same 'verse, while the second type, introduced in the sixth game of the RPG series and third game of the strategy series, were invading aliens called devils because some of them looked like mythological devils, with demons being simply one of their subspecies. The Ubisoft-verse has another story altogether.

Visual Novels

 * Shuffle has a demon race, and a god race. It basically means they're capable of magic, and they have long ears. Demons have longer ears than gods.

Webcomics

 * The Overfiends of Heartcore.
 * Reynardine from Gunnerkrigg Court is a talking mythological fox who gained body-snatching powers and subsequently lost his original body. Now he exists as some kind of fiery fox spirit that can't survive outside other people's bodies, which stinks for everyone else because he invariably kills his host. (This seems to be the sole reason why Sir Eglamore calls him a demon.) His cousin is a Trickster-god.
 * Zimmy, unkempt and nasty girl with freaky red eyes covered by black goo, was called a demon by Reynardine (who avoids touching her). Tom confirmed, though, that she's a human and it was just an invective in this case.
 * Though it seems pretty clear that human as though she may be, Zimmy isn't just a human.
 * It seems that in Gunnerkrigg Court "demon" is simply a pejorative used by people of ethereal beings that are dangerous, or that they simply don't like. Renard doesn't identify himself as demon, nor does anyone who befriends him. Likewise, he's prone of accusing Zimmy of being a demon, but no-one else agrees.
 * Order of the Stick is based on the Dungeons and Dragons rules, but gives it a little twist. The main fiendish character is Sabine, and debate still rages over whether she is a demon or a devil (see Tabletop Games above for the distinction). Haley couldn't tell which type of arrow (silver for devils, cold iron for demons) would penetrate her Damage Reduction, so she used both, and still isn't sure which one worked. OOTS also features the Inter-Fiend Cooperation Commission, an experimental alliance between Demons, Devils and Daemons, who seek to prove that the three factions can achieve more together than apart. Sabine (and now Qarr, who at least is definitely a devil) works for them, further obscuring the issue of what side she is actually on.
 * As for why no one can tell what Sabine is, both demons and devils feature attractive, winged, female creatures. Sabine most closely resembles a demonic succubus (she can shapeshift, drains life force, and describes herself as an "incarnation of illicit sex") rather than a devilish erinyes. However, she was sent to be the concubine of the explicitly lawful Nale. The revelation that she works for the IFCC might finally be an explanation for this, as it would give a reason for a chaotic being to be serving lawful interests.
 * The incredible [and sadly concluded] webcomic Demonology 101 by Faith Erin Hicks had demons that walk among people, but have pointy ears and teeth.
 * Some of the demons in Sluggy Freelance come from the Dimension of Pain. Others can be summoned through the Book of E-Ville.
 * Although as it was recently implied, the demons of the Dimension of Pain are less traditional demons and more like sentient creatures (human or othervise) transformed by magic and a poweful mutagenic compound.
 * Buwaro from Slightly Damned has GOT to be the worst demon ever. The only danger of dying with him around is death by hugs.
 * Demons in Heroes of Lesser Earth are of the summon via conjuring variety.
 * Demons in Kismetropolis are of the fallen angel variety.
 * Much of the conflict in Drowtales come from Demonic Possession.
 * Demon Eater The demons are cannibals and only transform after they eat.
 * Zebra Girl: The whole plot revolves around the accidental transformation of the title character from a normal girl into a demon, complete with hooves, bat wings, prehensile tail and pyrokinesis. It's a lot less fun for her than it sounds.
 * 8-bit Theater gives us incest, urine, and bad haircut demons.
 * In Chirault, "demon" is apparently a blanket term for a lot of different dangerous (or not) creatures. These include horned humanoids (like the protagonist, Kiran), cat girls (called Kyrions), emaciated frog-monsters, and titans made of mud and tentacles. Some of these are intelligent, and some aren't.
 * In Planes of Eldlor, an army of demons are lurking just on the other side of the rift, a gateway to their realm.
 * Darumatha in The Water Phoenix King is a classic Miltonian demon in many ways, announcing itself from the start as "The Demon-Dragon of Broken Hours," proclaiming its desire to overthrow the existing pantheon and rule the cosmos in turn, and tempting mortals to do its bidding with offers of unlimited power, glory, and treasure and/or Hannibal Lectures. It is also a shapeshifting entity bound from of old by the elder gods, whose default form is a world-spanning metal (yes, metal) serpent and whose preferred alternate form is that of a beautiful young woman. Despite having many good points to make about authority, righteousness and power, Darumatha has turned out to be definitely Evil. However, the difference between it and "the gods" is not so much a category one as a matter of metaphysical history being written by the victors, as the former ruling god and his angels were pretty horrible people themselves.
 * People in The Water Phoenix King tend to call any magical and/or dangerous thing a "demon" as well, such as shapeshifters, but this is not as careless usage as it first seems, since the lines are a lot blurrier than in Western mythology: anyone or anything can ascend to a "higher" level of being, given enough willpower, ambition, ability or training, and in theory become a demon/god if not defeated first. It's not easy, and it's not as if there are scads of ascending supernaturals around, but as in Eastern lore, it's possible: not all supernatural beings are the direct and deliberate creation of a deity.
 * In Wapsi Square, demons live in a separate world outside of our time line, attach themselves to sentient host creatures, and act in an advisory role. Most people can't see them directly, and they just seem to be a voice in the back of their heads. However, people can become living doorways to the demon realm, allowing them to see and speak to demons directly, and communicate with demons that aren't their own. In addition, if such a person dies under traumatic circumstances, such as a car accident, the demons can take control of the dead body, and continue to live without the host. They usually follow Blue and Orange Morality, but they do have a very strict set of rules.
 * DMFA has both angels and demons. The biggest difference between them is that the angels are subversive while demons are much more upfront.
 * The Demon in Friendly Hostility used to live in Fox and Collin's refrigerator. Not only is he not evil, he works as a nurse!
 * Demons in The FAN are psychic parasites that are formed as a result of powerful negative emotions in the minds of individuals with sufficient magical or psychic energy. They usually grow larger as they feed off these energies and eventually take over the host. Demons can be enslaved and called in using summoning magic. So far, their only weakness seems to be an enchanted camera that can trap and banish them.
 * Demons in Goblins are ancient entities from the deepest depths of reality (read: Hell) who are able to gain sustenance by inflicting suffering on the souls of other beings. They used to aquire suffering to consume by invading the realm of the gods and choosing some lesser divine entity to wage war against; when mortals came along, demons found them less satisfying as a meal, but the fact that they were plentiful and easier to subdue means many demons have switched to preying on them instead (Thunt, the author, likens this to a bear raiding trashcans in a suburban area). The concept of a Deal with the Devil arose because a demon who can aquire ownership of a mortal soul can torture it for the rest of existence, providing an infinite source of food. However, only the most powerful demons are able to take souls by force; most have to persuade a mortal to part with it willingly.
 * In Adventure Dennis the demons come in a variety of shapes and sizes and apparently live in Demonsylvania, ruled by King Demonevil. They kidnap the mayor because of his battery disposal policies.
 * In Adventure Dennis the demons come in a variety of shapes and sizes and apparently live in Demonsylvania, ruled by King Demonevil. They kidnap the mayor because of his battery disposal policies.

Web Original

 * In Soon, I Will Rule The World! this trope is invoked here and parodied here involving our world's demons taken from the Ars Goetia.
 * In The Antithesis, Demons only differ from angels by their phenotypes of black wings and dark hair. They live in the same world, but exist on lower layers of a planet that encapsulates Heaven and Hell, called "The Atrium". They do not possess the evil characteristics of the Judeo-Christian religion, but are actually a population of humanoid-looking beings, and their society contains moralistic values, political hierarchies (the highest being Lucifer, their leader/Military Commander/President, the second highest being the Archdemons) that formulate their Parliament, known as the "Obsidian Court". They are characterized with eccentric personalities, and their culture is embellished in art, literature, and theater.
 * Limyaael has a checklist of what to consider when creating demons.
 * In Demonic Symphony the demons are the embodiments of emotional energy projected on the world
 * In theory this means that there should be demons for other strong emotions such as love, but this isnâ€™t really touched on during the book.
 * In the online novel John Dies at the End, the demons turn out to be  Somehow, they are still affected by crosses, prayers and the Bible.
 * In Tales of MU demons need to feed from humans to survive, and they have a craving for human flesh well beyond said need... and most of the rest is hearsay. They do have a strong association with fire, and have been shown to possess humans and tempt them. The story also has another class of Petting Zoo People called "yokai" who in Fanon sometimes fall prey to the translation problem mention above.
 * The Salvation War has several different variants of demon. They are fallen angels, distorted by their environment. They invade 20th century Earth as part of the apocalypse. It doesn't work.
 * That said, even the angels and, by extension, are more akin to Sufficiently Advanced Aliens, with all their magic explained through various levels of EM field telepathy and generating of massive bursts of electricity, not to mention "body not built for flying" able to do so through internal sacs of gas that give enough buoyancy for their wings to lift... But tend to catch on fire or explode when damaged too much.
 * In The Questport Chronicles, many of the demons are said to be demon transformers who can take on any appearance they wish.
 * On the online Spec Evo project A Scientific Fantasy, demons are a family of giant lemurs.

Western Animation

 * The Legions of Hell in Teen Titans fourth season are mainly composed of floating, mute fire-creatures. A similar but scaled-up version with legs was summoned three seasons prior. But Trigon is even bigger, has blood-red skin instead of solid flame, antlers, and four eyes - basically Diablo with mutton chops instead of a tail.
 * The demonic creatures from Neighbors From Hell are basically as neurotic as people on Earth.
 * Jimmy Two-Shoes takes place in Hell, and the entire population is made up of demons. For the most part, they seem to have no special powers and are human in all but apperance. Word of God says that Lucius is a Reality Warper, but we never see it in action.
 * The demons in Plutos Judgement Day are all portrayed a jury of demonic cats.