Complete Immortality

This character can't die. This is because they are both of the following:
 * 1) The Ageless - The character does not age.
 * 2) Nigh Invulnerable - The character is completely immune to harm of any kind. The character may be Made of Diamond, or possibly an Intangible Man. Either that, or they are capable of regenerating their body under any circumstances. (Note that characters who are invulnerable but who age as normal are simply Nigh Invulnerable, not immortal.)

Most Physical Gods or Powers That Be fall into this category. A Time Abyss will tend to be this as well. This form of immortality can often be seen, especially by the afflicted character, as a curse. Or not.

Most fictional souls fit under this, if the work contains evidence of their existence. Ghosts can be banished to the underworld or sent on to the next life but not killed. Though there are exceptions.

Subtrope of Immortality.

Anime and Manga

 * Garterbelt from Panty and Stocking With Garterbelt, who was a Jerkass up until he got killed, then, with the blessings of God, became immortal and lived through all of the world's history from the dinosaurs to the present.
 * In Dragon Ball Z, the Filler and Non-Serial Movie villain Garlic Jr. wishes for immortal life from the Eternal Dragon. The only thing that stops him is knocking him into a dark prison called the Dead Zone (which presumably would kill anyone mortal), and the first time that didn't take. The second time around he has no way of ever getting out of there again, and will foreseeably be stuck there for all eternity while drained of most of his power.
 * The Big Bad from Ninja Scroll. If there was a way to kill him, none of the other characters found it.
 * Madoka Kaname from Puella Magi Madoka Magica wishes to, putting this trope into full effect.

Comic Books

 * Doctor Manhattan from Watchmen. The only thing that slows him down is the same thing that gave him his powers, and since he already overcame that problem to begin with, it's more of a minor hindrance than anything else.
 * In some incarnations, Superman, especially the Smallville version; in one episode a boy with the power to see how people will die (by touching them) touches Clark Kent and does not see a death, only some funky visual effects.
 * Mammoth Mogul from the Sonic the Hedgehog comics, is essentially an Alternate Company Equivalent of Vandal Savage. When he finally realizes he can't beat Sonic, he decides to simply wait until Sonic is too old to oppose him.
 * In No Hero,
 * In the Marvel Universe Amatsu-Mikaboshi was revealed to be this, being as it is the Anthropomorphic Personification of the nothingness before Creation. It is not only older than the universe, it is older than the universe before that and the one before that, stretching back to the Beginning.
 * In a more limited sense, the members Cosmic Compass who represent the Anthropomorphic Personifications of key universal concepts, such as Eternity, Infinity, Oblivion and Death, could arguably qualify, since they always exist so long as the universe does and when a new one comes along will exist in that one also, so though they do ultimately die when it ends they may also be reborn. Each of them are aspects of identical entities who operate on an even grander multiversal scale.
 * In Great Lakes Avengers, this is the only superpower Mr. Immortal has. One story reveals he's destined to live until the end of the universe.
 * In Phil Foglio's adaptation of Robert Asprin's Myth Adventures the evil socerer Isstvan has been cursed with immortality. You can blow him up and all the bits will just squelch together again (fortunately along with his clothes).
 * In Neil Gaiman's Sandman books, we see  death due to , and it's confirmed that an incarnation of   died once before the bulk of the comic is set, but, for the most part, the Endless fit this trope. Death and Destiny, especially.
 * Because of Death's immortality, an aspect of her becomes mortal for one day each century to keep her in touch with the lives she collects.

Fanfic

 * In Keepers of the Elements, all of the Immortals are this, but Radcliffe is losing his.

Film - Live Action

 * Almost all ghosts in Ghostbusters that are not at least a Class 7 are this, which is why they get trapped and sent into the containment unit.
 * In the film Wishmaster the Djinn claims to be this, to justify why nobody can simply wish him to die- as an eternal being, he simply cannot be destroyed.
 * In a similar vein, Satan in End of Days mocks The Hero for thinking he can beat him, since "you are just a man, and I...am FOREVER".
 * Ramin Bahrani's short film, Plastic Bag, ends with a lamentation by the narrator that amounts to "I wish I could die."
 * John Hancock and Marie Embrey from Hancock. They can be killed, however, if a specific circumstance happens:

Literature

 * The Tucks in Tuck Everlasting. They don't age, and nothing they've encountered yet can kill them.
 * In A Canticle for Leibowitz, if the old man really is the Wandering Jew, he's got this. (He's old, but he does not age. Assuming it really is the same man over all the sections of the novel.)
 * Eru from The Silmarillion and Tolkiens' other works is also this, being an Expy of God himself. The temporal, physical world was created partly for death to exist in the first place, in order to resolve the climatic conflict between Good and Evil.
 * Morgoth is the only true example of this in Middle-Earth. The elves are The Ageless, and most other Valar and Maiar can have their bodies destroyed, but can just make new ones. But Morgoth turned the entire planet into his Soul Jar, meaning he literally cannot die until the end of time. Doesn't save him from being a Sealed Evil in a Can at several points, but technically he's still out there, waiting...
 * The Ellimist and Crayak, from K. A. Applegate's Animorphs series. While not all-powerful, they are quite god-like, often use the Yeerks and the Animorphs as "chess pieces" in their game, and have been living for thousands if not millions of years.
 * Windle Poons from Reaper Man. He returns as a zombie, and despite the best efforts of his colleagues (and himself), he just will not die. However, it's possible he wasn't really a zombie, due to Death Being Fired, as other zombies are apparently capable of dying or at least being harmed.
 * The Divine Comedy: Not only God, but all souls are subjected to this kind of immortality, no matter if they are in Hell, Purgatory or Paradise. Their mileage varies about this status.
 * H.P. Lovecraft's Great Old Ones, or at least Cthulhu, have this form of immortality. In Call of Cthulhu Cthulhu gets a boat driven through his skull, turning his head into green paste. It reforms pretty much instantly. In writings of one of the later mythos writers, he's also gotten vaporized by a nuclear strike, only to reform himself. According to some writers, they can be killed by another Great Old One (or other godlike entity) while other sources state that they are completely unkillable.

Live-Action TV

 * The X-Files: Alfred Fellig in "Tithonus" was this until  It is possible that he passed this condition to
 * Buffy the Vampire Slayer: as part of the Mayor's Ascension he becomes completely unkillable and unharmable (but he's still a germaphobe). Once he completely Ascends he becomes killable, and Buffy kills him.
 * Captain Jack in Torchwood and Doctor Who is this. Blow him up and the body gradually begins to reassemble. He has been stated to age very slowly.
 * In Supernatural, Death claims he is the one thing in existence that will last forever.
 * The evil liquid entity Armus in the Star Trek the Next Generation episode "Skin of Evil" is stated to be immortal and unkillable. He has already spent an immeasurable amount of time on a barren, uninhabited planet after his creators left him there.

Myth, Legend, Oral Tradition, and Religion

 * God is usually understood to be this, being the Creator of absolutely everything, including Life, Time, Space, Death and whatever happens after it.

Video Game

 * The immortals of Lost Odyssey are completely indestructible in the story -- but Gameplay and Story Segregation means they function like From a Single Cell-like immortality during gameplay (can be hurt and "killed" during gameplay, but revive on their own).
 * The Unbreakable Darkness of Magical Girl Lyrical Nanoha As Portable: The Gears of Destiny, an Eldritch Abomination that was sealed in the Book of Darkness. Despite looking like a little girl, she's older than the previously established immortals of the series. She's also unable to die no matter how much she wants to, a fact demonstrated when she takes the strongest attacks in the entire franchise without receiving a scratch even when she's at just a fraction of her full strength.
 * Fujiwara no Mokou and Kaguya Houraisan from Touhou are immortal in the truest sense. While it functions like From a Single Cell they literally cannot die. Due to the laws of reality in Gensokyo when someone enters an area desegnated as the afterlife, where people can come and go, they count as dead. Mokou and Kaguya near literally run into a wall they cannot pass. One character has the power to cause anything to die at will. The two immortals are completely unaffected. They will probably exist til the end of time.
 * The Nameless One from Planescape: Torment and is therefore a true immortal in the exact literal sense. There are ways that will kill his body (thus, for all practical purposes of gameplay, kill him) due to ruining his Healing Factor (And I Must Scream scenarios, being killed by a God or god-like being like The Lady, cremation, dissolved in acid), but on a spiritual level he will never die: His spirit can never move on, he can never reach the afterlife, and

Visual Novels

 * Some of the more powerful beings in the Nasuverse have this. Entities like Ort, and Arcueid at the height of her power are so far removed from life as humans understand it that they do not have a 'death.'

Web Original
"Sometimes the discovery becomes massive and everybody in the world finds out at once and I end up on a pedestal. Sometimes they make me their leader, sometimes they call me an abomination, sometimes I get arrested and studied, usually it's all of this at once. I've been everywhere. I've done everything, spoken every language, built a pyramid, survived re-entry. History goes in cycles. If you watch it for long enough you can see the tipping points coming and be there when they happen. I invented fire, the wheel, the electric motor, antibiotics, you name it, every era, every country. Fought in X number of wars. Once, I actually ruled the whole world.
 * The Narrator of Immortality Blows has immortality "so perfect" that he/she survives the end of the world
 * The golem girls in Wapsi Square have this kind of immortality.
 * The character Anne Poole, from Fine Structure, is cursed with this form of immortality. She is indestructible and immortal, which becomes a problem near the beginning of the story when she's accidentally teleported into solid rock. By the time they get to her, she's gone insane from deprivation. Of course, she eventually gets better, and she goes on to live tens of thousands of years longer; it's revealed that she actually goes through phases of insanity, as the human mind isn't meant to have that kind of continuity.
 * From the woman herself:

I've walked on the Moon barefoot."


 * The SCP Foundation:
 * SCP-682 is described as a "Hard-to-Destroy Reptile". It's basically a homicidal, regenerating dinosaur that adapts to whatever you throw at it. They haven't tried things like nuclear bombs on it yet, because the last thing they need is a radioactive, red hot homicidal indestructible dinosaur. Between experiments, they keep 682 stored in a tank of acid, because while that won't kill it, not having a muscular structure will at least make it hard for it to cause any trouble. Though it still manages to break out of it occasionally.
 * There are other complete immortals in the SCP holding cells, including the Demon Born of War and Abel, but 682 is probably the most famous.

Western Animation

 * The Justice League incarnation of Vandal Savage appears to be a complete immortal: He doesn't age and shrugs off practically all damage. During his three appearances he, , and finally . None of this seems to bother him,