Guilt-Free Extermination War

""Either we spread and wipe out the Bugs, or they spread and wipe us out - because both races are tough and smart and want the same real estate.""

- Juan "Johnny" Rico, Starship Troopers

You know how most wars end when one side gets what they want, or stops caring, or the other side surrenders? This is not that kind of war. This is a war where the only possible outcome is the utter annihilation of the other side. This isn't Good Versus Evil either, where one side wins forever and there's sugar and gumdrops for the rest of eternity, this is two sides fighting to the death for reasons that cannot be summed up. Other options are neither explored nor put forth as viable in any way. Don't expect either side to feel guilty either.

This is when both sides have no issues in trying to destroy the other side, and the only way that the war will end is with one side's destruction. Peace is not an option, and the only end is when the other side is destroyed entirely and there are no survivors. It may not even be a war: it may just be a natural enemy that is a constant danger to the Heroes, like the Zombie Apocalypse. Don't expect An Aesop or musing about how war is terrible or The Hero is becoming like their enemies. There won't be an agonizing decision about whether or not it's okay to decimate enemy forces if the chance arises. These enemies aren't just okay to kill individually like Mooks, these enemies are okay to exterminate in their entirety. However, one side keeping the other around as food or nurseries fits in as well.

Frequent users include: Zombie Apocalypse, Bug War, Robot War, Horde of Alien Locusts. Compare Always Chaotic Evil for when The Hero consider the enemy to be guilt free, but don't engage in a protracted war. Compare Final Solution, which isn't necessarily a war or an instance of Blue and Orange Morality or one side does it but the other side is unwilling to. May eventually wind up with Would Be Rude to Say Genocide.

Anime & Manga

 * Mushishi, while Ginko is normally a Friend to All Living Things and incredibly forgiving to even the most violent or dangerous mushi, his response when confronted with a species of Mushi that exists solely by preying on people is to explain calmly that humans and that breed of mushi cannot coexist, and humans are stronger.
 * In Gunbuster, the space monsters are described as a galactic "immune system" trying to wipe out the "disease" of humanity. Humanity is aware that their winning may carry consequences for the galaxy, but decides "Fuck that, we're gonna try to survive anyway."
 * Mobile Suit Gundam SEED: The war devolved into this after the destruction of the Eurasian military forces at JOSH-A, the Earth Alliance was quick to adopt extremely dubious policies like using drugged up biological computers for their own bidding and ZAFT used Genesis to gruesomely wipe out the enemy. The Veigans and Earth Federation Forces also apply in Gundam AGE, all of the Veigans are fanatically loyal to Elzecant and the Earth Federation knows nothing short of the extermination of the Veigan will stop them.

Comics

 * Metabarons Universe humanity is threatened by an alien invasion. Rather than waste resources fighting a war, they agree to a battle between two champions. The loser commits "immediate racial suicide." This is perfectly in keeping with the Metabarons storyline, where everything is cranked Up to Eleven.

Film

 * Terminator: in the future humans vs the robots.
 * Independence Day: the aliens, in keeping with their Horde of Alien Locusts, have no issues wiping out entire cities full of people.
 * The US President actually does probe for peace even after they destroy every major city on Earth, with an alien that had just slaughtered a team of scientists no less; the response was a Mind Rape that would have killed him if the alien wasn't shot, and it showed him that their entire civilization is based upon this, moving from one world to another, wiping out the natives, using up all the resources, and then moving on to the next planet to repeat.

Literature

 * Pandora's Star includes an implacable hive mind whose only motivation is to be the last sentient being in the universe and has no problem wiping out humanity. Given that its entire species consists of a single individual, victory for humanity would by definition leave it extinct.
 * Lensman stories by E.E. "Doc" Smith: The conflict between Civilization and Boskone was a fight to the death. Neither the Galactic Patrol nor the pirates of Boskone ever surrendered to the other, and entire planets were destroyed in the conflict.
 * Starship Troopers by Robert Heinlein: The war between the Terran Federation and the Bugs (Arachnids).
 * Retained in the adaptations, though they turned the Bugs into non-technological alien locusts, as opposed to the tool-using Hive Mind in the book that even had allies.
 * Old Mans War by John Scalzi initially presents humanity in a constant state of war with other species for colonies, using a similar justification to that of Starship Troopers (one of Scalzi's inspirations) in that "this galaxy ain't big enough for the two of us". But.
 * Lord of the Rings: the humans and elves vs the armies of Mordor. The closing section of The Hobbit talks quite pleasantly about the goblins being hunted into extinction in the Misty Mountains, without any hint that anyone could have a problem with this.
 * The Doctor Who Expanded Universe novel Sky Pirates! revealed that the Timelords had a couple of wars like this in the distant past, where the opponents were just so utterly different each side regarded the other as an Eldritch Abomination to be utterly eliminated. The Timelords won.
 * The Bible is the Ur Example, as the Hebrews are ordered by God to displace and destroy the Canaanite people. This is supposed to be okay because they practice child sacrifice and temple prostitution, and also because the 'curse of Canaan' says it will happen. It's up to the reader whether this is Values Dissonance or not.
 * In the Codex Alera, the conflict between the Alerans and the Vord. Most of the Vord are mindless beasts under the control of their Queens, which have a genetic imperative to wipe out any other species and expand to consume all. There is also the war between the Vord and, which ultimately ended with  , save for the ones that.
 * Related to the Starfire example in Tabletop Games is the novels based off it by David Weber and Steve White. In addition to the war with the Rigellians as part of the back story there is the war with the Arachnids or Bugs. No attempt at communication succeeds and they view other sentient species as nothing more than food. The only world that is not subjected to massive orbital bombardment is the homeworld of one member of the Crucian Alliance which is liberated the hard way.
 * The Inheritance Cycle. The Always Chaotic Evil Ra'zac are exterminated, first by the Riders and then by the protagonist. The moral rectitude of this action is never questioned.
 * Ender's Game: . Card's later Ender books establish a scale of "alienness" between individuals and species, where on the farthest end of alienness it becomes possible to acknowledge that avoidance or xenocide are the only options for interaction between species because they simply cannot comprehend one another. The moral burden is upon the would-be exterminator to make certain there's no way to communicate with (or just avoid) the other species before committing to the extermination war, however.
 * Star Wars Expanded Universe
 * The Black Fleet Crisis: The main villains are the Yevetha, who are your typical Scary Dogmatic Aliens -- they're well able to learn Basic and sent someone to meet with the New Republic, fair enough, but they only do this as the prelude to starting a war with it, in which we see that they are impossibly xenophobic and culturally narcissistic; their culture had developed and become advanced with not a single recorded speculation that there was other intelligent life in the galaxy, and First Contact only convinced them that everything else was unworthy vermin which had to be exterminated. Every member of the species was prepared to die fighting, but after winning the New Republic just destroyed all of their ships and left them stranded on their world. Years later, when the Yuuzhan Vong with their similar if not quite as extreme xenophobia showed up, the Yevetha refused to submit and were hunted down and systematically killed.
 * The Bothans have this as a little-used cultural practice called ar'krai. Every able Bothan is required to volunteer for military service in order to not only slay every last member of the offending group or species, but grind their homeworld to dust. They declare ar'krai against the Yuuzhan Vong after perennial Obstructive Bureaucrat Borsk Fey'lya pulls a Heroic Sacrifice during the fall of Coruscant.
 * In Last and First Men the Fifth Men kill off the native Venusians without a second thought. Of course, by then earth was dying and Venus had to be terraformed to be inhabitable.
 * The Martians in The War of the Worlds have this attitude toward humanity; the humans are too busy being terrified and/or dying to return the sentiment.
 * In Garrett P. Serviss's unauthorized sequel Edison's Conquest of Mars the humans fly to Mars and cheerfully wipe out the Martians who tried invading Earth. Technically it's an accident, but nobody's really bothered by the extermination of a whole species.

Live Action TV

 * In Doctor Who, the war between the Thals and the Kaleds would only end with one destroying the other. The Thals "won" by destroying the Kaled bunker thanks to information leaked to them by Kaled scientist Davros - who then turned his creation, the Daleks, on the Thals, thus destroying them as well.
 * The Daleks themselves are utterly convinced that every single non-Dalek lifeform in the universe must be exterminated; they are also genetically engineered to feel "no emotion but hate", and once engaged in a mutual civil war of annihilation when Davros made a new breed with only trivial, aesthetic differences between them. The Doctor himself varies on the issue; on rare occasions he will try diplomacy or some more peaceful tactic, but on plenty of others he's more than ready to literally Kill'Em All, and is horrified when Joker Immunity kicks in and a handful, or even a lone, Dalek survives.
 * As was said in the new series episode where the Cult of Skaro first encountered the Cybermen: "THIS IS NOT WAR! THIS IS PEST CON-TROL!"
 * The Last Great Time War seems to be this as well, from what little we know of it. The Time Lords and Daleks seemed to be out to simply destroy each other, and at some point the Doctor decided that both sides had to be destroyed.
 * The humans on Battlestar Galactica, for the most part, believe this since the Cylons wiped out 99.99999% in the pilot. They will frequently torture and kill captured Cylons because they're "just machines" and don't really feel pain. People who object are typically just written off as incredibly naive or crazy..
 * Stargate Verse:
 * Stargate SG-1: the replicators will consume anything and everything to replicate, and the only way to stop them for good is to wipe them out, so the war with them inevitably becomes this. A different type of replicators appear in Stargate Atlantis, and this applies to them as well.
 * Stargate Atlantis: the fight against the Wraith is generally seen as an us-or-them game as well -- the Wraith might not be out to kill all humans, but that's only because they need to keep them as a food supply. Later on, Dr. Beckett develops a virus that turns Wraith into humans, but it wears off without regular boosters and is nigh-impossible to deliver. Even later the Replicators and renegade Asgard force the Atlantis expedition into multiple Enemy Mine situations with one Wraith faction and at one point offer them an experimental treatment that would allow them to live without feeding on humans.

Tabletop Games

 * In Warhammer 40000, nearly every single race has reasons and plans to exterminate every other race.
 * This is quite literally the Imperium's standard colonization protocol: drop a few Imperial Guard regiments, exterminate all sentient life on the new planet, ship colonists in.
 * The Tau don't automatically exterminate every species they come across, preferring to integrate and "adopt" other species as they discover them. Still, when they do encounter a species that they determine unfit or unable to peacefully coexist, they will ruthlessly exterminate them. Considering the galaxy they live in, this proabably happens pretty frequently.
 * Eldar will usually avert this trope, since they tend to work more subtly, through subtly manipulating the galactic stage to keep themselves as far out of harm's way as they can manage. Played with, with the Dark Eldar, who legitimately enjoy murder but actually prefer to abduct populations and capture their enemies. One of the taglines for their army list was "Pray they don't take you alive."
 * Tyranids exist to eat, breed and absorb the best characteristics of every species that they can get their claws on -- only characteristics that facilitate those three imperatives, of course.
 * The Necrons serve beings that wish to annihilate everything related to the Warp. The Warp is sustained in part by the emotions of living beings. Nothing more needs to be said.
 * Starfire by Task Force Games: The Third Interstellar War between the Alliance (Terrans and Khanate of Orion) vs. the fanatically racist and warlike Rigelian Protectorate. The Rigelians were determined to wipe out the Alliance, and the Alliance was forced to destroy the Rigelians completely to eliminate them as a threat.
 * Magic: The Gathering deals with this whenever Phyrexians get involved, especially in Invasion and Scars of Mirrodin blocks.
 * Dungeons and Dragons has the Blood War between the Lawful Evil devils/baatezu and the Chaotic Evil demons/tanar'ri, it's been raging for millenia and is unlikely to end until and unless one or both sides gets totally exterminated. Which is fortunate for everybody else because the fiends could probably wipe out the celestials and everybody else in the multiverse if they weren't so busy fighting each other.
 * Frequent in 3:16 Carnage Amongst the Stars. Because it's us or them.

Video Games

 * Total Annihilation: Both factions use this and have to be sure they've wiped the other side out or they'll just rebuild with Nanotechnology.
 * In Mass Effect, the battles against the Reapers' indoctrinated servants, played a few different ways.
 * The rachni were hunted to extinction.
 * The turians and salarians used a Depopulation Bomb the end the Krogan Rebellion. (Defied Trope; the Genophage was made specifically to avoid this trope, and was originally intended by the salarians to be a deterrent)
 * Shepard is personally responsible for wiping out the Collectors.
 * Shepard is forced to choose Heel Face Brainwashing or destroying the  geth.
 * In general, there's a standing order in Council Space that all AIs are to be terminated on sight. The exceptions are those which are authorized by controversial research companies such as Synthetic Insights. Knowing that every organic in the galaxy is united to kill them without a second thought, many synthetic creatures (such as the geth) shoot first and ask questions later.
 * The only option (other than Assimilation Plague) in Sword of the Stars before the second expansion added psychology techs that allow a player to force a planet to surrender after just one or two nukes.
 * In Star Fox Assault the Aparoids are exterminated without a second thought. And in at least some of the possible endings to Command the Anglar are presumably wiped out as well (considering their homeworld is terraformed in a couple endings).
 * In Ratchet and Clank: Tools Of Destruction, pretty much everyone who brings up the subject considers the Lombaxes the "Saviors of the Universe" for completely wiping out the Cragmites.
 * Starcraft: the Zerg are a race burdened with a hard-coded biological imperative, instilled by the Xel'Naga, to assimilate and destroy other species. The absolute best that could possibly be done short of true extermination is destroying the Overmind to reduce them to merely very dangerous animals.
 * The Human-Covenant war starts out this way in Halo, the covenant goes to far as to completely destroy each Human planet they encounter. That is, until the Elites get  Played thoroughly straight with the Flood.
 * In Perfect Dark, Joanna teams up with the Maians in the last two levels to exterminate all the Skedar fanatics. This is not remotely depicted as a bad thing, because they have a Hive Mind and can't be reasoned with.
 * The Human-Locust War in Gears of War is one of these. The Locust want to exterminate humanity so they can have the surface of Sera, and the humans want to exterminate the Locust in self-defense. The Lambent also get in on this when they show up, making it a three-way Guilt-Free Extermination War.
 * The war against the Kreegan in Heroes of Might and Magic III: Armageddon's Blade becomes this after Erathia drops out. The remaining anti-Kreegan forces are well aware that the 'Devils' are a severe threat to the world (even if they aren't aware of the full scope of the threat), and finishing the war to the bitter end is really the only long-term option, while the Kreegans built the titular Armageddon's Blade to burn the world. Even before Erathia dropped out, the problems the nobles had with a campaign of extermination wasn't the extermination, but rather the cost in troops and gold.
 * In Wing Commander, the war between the Kilrathi and humans was this for the Kilrathi from the start, and for the humans it became so after faking a desire for peace to build up a massive fleet that was used to completely sterilize several planets, with Earth on the list for the same treatment before being interrupted as shown in the novel Fleet Action.

Real Life

 * Germs vs. humans for the most part. For the most part, this constitutes a "humans vs. creatures-motivated-by-wanting-to-eat-them".
 * The first disease we've been able to exterminate so far was smallpox. The only surviving samples are around for research.
 * On 8 August 2011, the United Nations held a ceremony declaring rinderpest eradicated - the second disease to be fully wiped out.
 * Not a germ, but closely related to one. The small, silvery mosquito called Aëdes aegypti (beforehand, Stegomyia fasciata) used to spread yellow fever in the Americas. It has been, ahem, disappeared from the Americas. (A silent nod to DDT...) More on how yellow fever destroyed Memphis after the Civil War is at http://www.americanheritage.com/content/epidemic
 * There is an enterprising Mad Scientist who is planning to exterminate mosquitos... with "layzorz!" We can only wish him the best of luck.
 * The relationship between many competing species. As a rule if two species occupy the same niche the carrying capacity of the environment is decreased due to competition. For example, a forest might support 400 coyotes or 600 foxes, but if both species are present it might only support 150 coyotes and 250 foxes, less than half the normal carrying capacity for either species.