Some fictional and mythological beings are completely immortal (or very nearly so) in that they are immune to death by injury, disease and age. Examples include various types of gods. Sometimes such powerful immortals can only be killed by each other, as is the case with the Q from the Star Trek series. Even if something can't be killed, a common plot device involves putting an immortal being into a slumber or limbo, as is done with Sauron in J. R. R. Tolkien's The Lord of the Rings and the Dreaming God of Pathways Into Darkness. Storytellers often make it a point to give weaknesses to even the most indestructible of beings. For instance, the Greek hero Achilles was supposed to be invincible, yet his enemies were able to exploit his infamous weakness, Achilles' heel, to slay him.
Many fictitious species are said to be immortal if they cannot die of old age, even though they can be killed through other means, such as injury. Modern fantasy elves often exhibit this form of immortality. Other creatures, such as vampires and the immortals in the film Highlander, can only die from beheading. In Harry Potter, witches or wizards are able to become immortal by creating horcruxes (as long as the Horcruxes are not destroyed) or by drinking the elixir of life, made with the Philosopher's Stone, though the Elixir must be drunk often to maintain the immortality.
Immortality can be used as a prize, something to be earned by great achievement. Legendary heroes, great magicians and wise elders sometimes rise to the ranks of immortality in fiction and mythology. It can be the reward at the end of a great quest, such as the quest for the Holy Grail or the ancient Epic of Gilgamesh. When immortality is something that can be bought, works of fiction will often make judgements regarding the high price that must be paid. Immortality is often the desire of evil characters as well. If immortality is something that can be earned, then it can also be taken away, much to the dismay of many an immortal villain.
Tezuka Osamu's lifework Phoenix (known in Japan as Hi no Tori) had a phoenix whose blood would provide immortality. In various ages, many "heroes" and "heroines" would strive for immortality only to realize that there is something beyond eternal life. In one story titled "Raise hen" (lit. "Next World Story") the last remaining human male who survived a holocaust, blessed (or cursed) with immortality through the phoenix blood, would create another beginning of life. In his immortal form, he would see a race of slugs, after gaining intelligence, destroy themselves in another holocaust. He would seed the earth with life that would become present day humans, and finally leave the earth to join his lover, who died billions of years ago, in heaven.
In the Cthulhu Mythos created by H. P. Lovecraft, there is a race of "Fish-Men" known as Deep Ones. They stop aging after reaching adulthood and can breed with humans to birth offspring with this "eternal youth." Though this is a faustian bargain, as after reaching the age of 20, the Deep One Hybrids undergo a transformation from normal humans into hideous Deep Ones. They also lose all concept of humanity and morality and go to live in the ocean with the Deep Ones and to worship the undersea deity Cthulhu, the Lord of Madness.
In some parts of popular culture, immortality is not all that it is made out to be, possibly causing insanity and/or significant emotional pain. Much of the time, these things only happen to mortals who gain immortality. Beings born with immortality (such as deities, demigods and races with "limited immortality") are usually quite adjusted to their long lives, though some may feel sorrow at the passing of mortal friends, but they still continue on. Some Immortals (such as certain deities, demigods, and intelligent undead) may also watch over mortal relations (either related to or descended from them), occasionally offering help when needed.
In his short story 'The Immortal', Jorge Luis Borges treats the theme of immortality from an interesting perspective: after centuries and centuries, everything is repetition for the immortal and a feeling of ennui prevails. The immortal, who had turned so after drinking from a certain river, is set to wander the world in search for that same river, so that he can become mortal again.
In J. R. R. Tolkien's Middle-earth mythos, the immortal Elves were said to view the mortality of Men to be a gift. This was chiefly due to the Elves' clear faculty of memory, which could accumulate millennia of sad experiences.
The Dungeon Master in Zork Grand Inquisitor, a spirit in a lantern during the game, accidentally casts an immortality spell on himself while he still has his body. He soon grows terribly bored, and tries many ways of suicide, with little or comical effects, for example: "Dear Diary, today I tried to kill myself by shoving a sword through my heart. All I got was heartburn."
Another rather comedic incident involving an accidental cause of immortality can be found in Douglas Adams' Hitchhikers guide to the galaxy, where the alien Wowbagger accidentally turned himself immortal. Due to not being a natural immortal, people who he considers to be "a bunch of serene bastards", he doesn't know how to handle his immortality and winds up deciding that he will insult every living being in the universe - in alphabetical order just to kill some time, something he has an awful lot of. In the radio adaptation, his immortality is removed right before the End of the Universe after insulting a deity.
In the manga Blade of the Immortal, Manji is a samurai who has been cursed with immortality. Only after slaying 1000 evil men will the curse be broken so he can finally die. His body cannot age nor can he die from physical wounds. Manji's sword skills are sloppy due to the fact that since he's immortal he doesn't need to know how to fight properly. There is another immortal character in the Naruto series named Hidan, who claims to be the slowest attacking member in his group and is considered stupid by his partner, because he attacks without thought for the consequences. It is possible he did not gain these skills because he did not believe he would need them, being an immortal. This could hardly be further from the truth: Hidan is now a disembodied head buried under a ton of rock, and yet cannot die.
In legend, most famously in Wagner's opera The Flying Dutchman, a ship's captain is cursed with immortality after attempting to sail around the Cape of Good Hope in a terrible storm. He is doomed to sail around the Cape forever.
In Jonathan Swift's Gulliver's Travels, some of the inhabitants of the island of Immortals (near Japan) don't die, but they age and became ill, demented and a nuisance to themselves and those surrounding them. Swift presents immortality as a curse rather than a blessing. The film Zardoz also depicts a dystopian view of immortality, where interest in life has been lost and suicide is impossible.
The Star Trek: Voyager episode "Death Wish" explored in depth the existence of the omnipotent, immortal and omniscient aliens Q. It is learned in that episode that the aliens were originally human-like, and somehow evolved into their current state long ago. With their new-found powers, the Q set out to fully explore, experience and understand the universe. Afterwards, the Q had nothing left to do or say, and now they simply sit out eternity in their realm. As one Q explained, you can only experience the universe so many times before it gets boring.
In the children's novel, Tuck Everlasting by Natalie Babbitt, a family is made physically immortal by drinking water from a magical spring. They are trapped at the same age forever and are invulnerable. They are hated by the ordinary people who knew them and are forced to watch as everything they cherish grows old and dies.
In the film and television series Highlander, once one dies for the first time, if they are an Immortal, they will spend the rest of eternity at that physical age. This poses a problem when one dies as a small child, or as a very old man. The same is true of Kirsten Dunst's character in the film Interview with the Vampire, who became a vampire while still only a child, and the Blade television series.
In the Legacy of Kain series, vampirism was a curse placed upon an ancient race that won the war against the Hylden that granted bloodlust, sterility and immortality, the latter causing their God to abandon them.
In the movie Death Becomes Her, the characters of Madeline Ashton and Helen Sharp both become immortal and young after drinking a potion, but this form of immortality has significant drawbacks; most significantly, unlike most forms of immortality, which include rapid healing from injuries, Madeline and Helen simply stop aging from the moment they drink the potion, and subsequently don't stop moving even after their bodies die. As a result, they continue to decay despite the fact that they are still conscious, regardless of the injuries they sustain in the process; in the course of the film Madeline's neck is broken and a large hole is blown in Helen's stomach, with both of them shattering into pieces in the final scene of the film, and yet both continue walking and talking as though nothing had happened. At the conclusion of the film, it is shown that the two are now forced to stay together for all eternity in order to ensure that their bodies remain in at least partially decent condition, despite their own long-term enmity for each other.
In general, a theme seen with many variations, is the notion of an essential world weariness akin to extreme exhaustion for which death is the only relief. This is inescapable when immortality is defined as (half) infinite life. Immortality defined as finite but arbitrarily long per the existants desire does not, as a definition, suffer this limitation.
When a person is tired of life, even death is shut off to them, creating an endless torture, as evidenced in the Bill Murray movie Groundhog Day, where a character is trapped in an endlessly repeating time loop that causes him to live the same day over and over again even when he tries to kill himself before the end of the cycle.
The roleplaying game Vampire: The Requiem, published by White Wolf Publishing, Inc., has undeath be the form of immortality held by vampires wherein their bodies are absent of all life functions such as breathing and heartbeat. They have theoretically infinite lifespans (and can even survive unprotected in the vacuum of space and under the crushing depths of the ocean), but they can be killed with enough damage. Though they are also forced to watch as everything they knew in life withers away and they are unable to adapt to the changing eras of history. Because they are fallible predators, their humanity also begins to deteriorate, and a few become mindless/insane monsters called Draugr (also known as Revenants) as a result of losing all concept of being human. Such ravening monsters are always hunted down by other vampires, to prevent humans from learning of the existence of vampires.
The character Raziel from Legacy of Kain is a wraith whom is capable of passing between the spirit world and manifesting in the living/material realm. Due to his secondary remaking into a wraith, he is beyond the cycle of death and rebirth so therefore cannot be killed. Any significant damage done onto him in the living realm forces him to seep into the spirit world to heal and any fatal damage in the spirit world simply transports him back to the Elder God or an activated checkpoint.
In the films Re-Animator, and subsequently Bride of Re-Animator and Beyond Re-Animator, Dr Herbert West creates a serum that has the ability to re-animate dead tissue and stop its decay. In Re-Animator, re-animated corpses are shown to show some emotion and intelligence if they're fresh enough. However, the antagonist in the story lobotomizes re-animated decaying corpses to make them his slaves.
Freddy Krueger of the A Nightmare on Elm Street movies is considered to be immortal, as well. Though he was killed as a human, he exists as a "dream demon", who needs only to be feared to be able to enter people's dreams and cause them harm. Even without this fear, he can exist, either in "limbo" or in Hell. Because of this immortality, he can never be permanently killed. He can only be contained by being forgotten about, and thus prevented from ever entering dreams again.
In the movies and television series Highlander along with its franchise, the main characters of Connor MacLeod, Duncan MacLeod, and Methos, with other characters, are immortals since they are immune to disease and stopped aging after they had their first death, they can live forever and they only can really die when they are beheaded.
In Doctor Who mythology, the Cybermen are basically human brains placed into mechanical bodies, with every emotion drained out. This process was supposed to allow the Human race to reach its pinnacle. The unforeseen downturn is that with immortality reached, there is no motivator for the Human Race to actually strive for anything more. In another Doctor Who storyline, The Caves of Androzani, a fictitious substance named spectrox, found exclusively on the titular planet, is revealed to be able to prolong human life to more than double its natural length, and as such is the most valuable substance in the galaxy - ironically, the lives of all those involved with it in the story are grim and difficult, due to corporate monopolizing of its distribution, and the resultant infighting over its control, extortionate costs and the theft and smuggling of the substance from its mines.
Another example of immortality in Doctor Who is found in the character Jack Harkness, a companion to the Ninth and Tenth Doctors, who was unintentionally transformed into a 'fact' of the timeline when fellow companion Rose Tyler temporarily acquired omnipotent power and brought him back to life after he was killed by the Daleks; unused to the power, Rose didn't just bring him back to life, she 'brought [him] back forever'. Although he ages at a very slight rate- having grown only the occasional grey hair despite having been alive for over a century since he was resurrected-, Harkness is capable of recovering from any potentially fatal injuries within moments, although some forms of death take him longer to recover from than others; a bullet to the head only put him down for a few seconds, but he required at least a few minutes to come back after being thrown from the roof of a tall building. In the spin-off series Torchwood, Jack's colleague Owen Harper acquires a similar kind of immortality when he is brought back to life after being shot; although Owen is now technically dead, and is thus incapable of eating, drinking, sleeping or having sex, as well as being unable to heal if he is injured, he is also practically unkillable, apparently lacking the need to breath and displaying a general immunity to pain, as demonstrated by him not noticing that he had cut his left hand. Owen compares his new state to Jack by saying that, while Jack will 'live forever', he is destined to 'die forever'.
Megaman Zero's Doctor Weil had his memories transferred into program data and his body remodeled into that of a cyborg's as punishment for sparking the Elf Wars, using the Dark Elf to attack Reploids and humanity alike. He was then banished from nature and humanity, which eventually drove him insane.
In the TV series Stargate SG-1, the primary antagonists for the first eight years, the Goa'uld achieve a measure of immortality. The Goa'uld symbiote can naturally extend the life-span of its human hosts upward of 200 years. By coupling its own natural healing abilities with advanced technology, a Goa'uld can keep itself and its host alive almost indefinitely. However, during the later seasons of the show it is noted that the Goa'uld, even when using life-prolonging technology, change hosts after a number of millennia. Additionally, Lord Yu, one of the oldest Goa'uld, started experiencing similar symptoms to old age (such as memory loss) as his host had become too old to be regenerated by the technology, and the symbionte itself was now physically unable to take a new host due to old age. The Goa'uld do experience a different measure of immortality as they possess genetic memory, so any direct descendants will have all the memories of their predecessor. This is passed on down the generations of the Goa'uld, so one could say a part of the Goa'uld lives on forever. In the spinoff to SG-1, Stargate Atlantis, the main villains, the Wraith, who drain the life force of human beings to survive, can't die of natural causes, and are difficult to kill by force (their toughness depends on the time of the last feasting). In the episode "The Defiant One", a Wraith remained alive for over 10,000 years by cannibalizing other Wraith when its original food source (captured humans) was depleted. Both series feature "ascended beings," such as the Ancients, who have learned to shed their physical body and exist as energy, making them immortal.
Perry Rhodan is the world's most prolific literary science fiction (SF) series, published since 1961 in Germany. In the storyline Perry Rhodan is the commander of the first mission to the moon, where they come upon a stranded vessel of an alien race in search of eternal youth. Perry Rhodan uses the superior technology to unite the earth and then continues the search for eternal youth. Ultimately he follows the hints laid out by a higher being called ES ("it" in German) that exists in an incorporeal state. This being chooses Perry Rhodan and a select few of his companions to attain Agelessness (ES says "I grant you everlasting life, not rejuvenation") in order for them to pursue goals set by ES.
In the Hyperion Cantos Universe, a parasite originating from the planet Hyperion called the cruciform brings immortality, being able to regenerate the body after death. Wealthy humans can also achieve significant increase of their life expectancy thanks to the expensive Poulsen treatments.
In the novel Ender's Shadow a genetic modification known as Anton's Key is discovered, allowing the human mind to achieve supreme intelligence at the cost of an extremely short life, and it is said that the reverse can be done, making a person immortal at the cost of nearly all intelligence.
In Tad Williams' Otherland novels, the Grail Brotherhood, a group made up of the most affluent people in the world, attempt to achieve eternal life in virtual reality. They try to copy their neural pathways into virtual replicas with all of their memories, then kill their physical forms. The process fails due to complications involving the system's artificial intelligence.
In the LucasArts adventure game The Dig, the remains of an alien civilisation advanced enough to gain first physical and then spiritual immortality are explored and analysed. It eventually turns out that the obsession with living forever ultimately brought about their downfall; they lived forever, but lost "everything that made life worth living".
In the game Warhammer 40,000 set thousands of years in the future and across the galaxy, the Necron race are virtually immortal, their souls placed in machines that can be revived from any damage. And the C'tan, beings of pure energy living in artificial bodies, are immortal and can only be fully destroyed by another C'tan or by a Warp-based attack, such as a Talisman of Vaul.
In the Richard K. Morgan novel Altered Carbon their consciousness rotated into a new clone when they die. Certain wealthy called "Meths" (short for Methuselah) can afford to have their consciousness rotated through a series of perpetual rejuvenated clones, thus avoiding old age. It is wryly noted however, that most people don't have the stomach to experience old age and death more than twice, and opt to be "put on stack" (stored) except for special family occasions.
Most of the novels by Alastair Reynolds feature immortal characters of some form or another, usually made possible by advanced medical technology and periodic regeneration of one's body. One of the issues discussed in these novels, particular Chasm City, is the manner in which characters deal with their immortality and the boredom it inevitably generates. The Conjoiners, the most advanced faction, are able to modify their brains to the extent that they simply do not experience boredom at all. Unagumented humans typically suffer intense boredom and attempt to reduce this by taking part in increasingly dangerous and exciting activities.
Relativistic interstellar travel granting virtual immortality is used as a plot device in Orson Scott Card's series of novels involving Andrew (Ender) Wiggin. Gravitic devices such as the stasis field are used in the Known Space universe created by Larry Niven. This kind of immortality is, however, illusionary. The "slowing" effects of time dilation also extend to all functions of the brain; thus, while to an outside observer the traveler's life would seem greatly extended, the slowed individual would not actually experience his life as any longer than before and would age at the regular speed, relative to his own time frame.
Unstuck in Time - The idea, postulated primarily in Kurt Vonnegut's Slaughterhouse Five, that one can become unstuck in time, and spend (at least theoretically) eternity in various points of their life. While this person would still die and cease to be, their life would not, in essence, end, as they would eternally wander about their life. In the particular example of Slaughterhouse Five, the main character, Billy Pilgram, meanders about his existence, reliving war experiences, an alien abduction, and his eventual assassination. Whether this would qualify as immortality is debatable.
X-Men's Wolverine is a character with keen animal-like senses, and whose mutant healing abilities made it possible for a specialized fictional alloy called adamantium to be grafted to his entire skeleton without the subsequent metal poisoning killing him almost instantly, with the addition of 2 sets of 3 razor-sharp claws that extend from each hand. Each time he projects the claws, they cut through the skin of his knuckles, but the slick design prevents any bleeding from occurring. The cuts the blades create instantly heal once they're retracted.
The Doctor Who series focuses on a character called The Doctor who is famous for regenerating instead of dying or aging; however, rather than simply healing wounds, this results in his entire physical appearance changing when he is fatally wounded or terminally sick, and he is only capable of doing so twelve times before finally dying for good. The Tenth Doctor expressed regret that he would eventually lose all his companions, while he himself would live on: "the curse of the Time Lords".
In the Doctor Who story The Five Doctors, Lord President Borusa of Gallifrey uses the first five regenerations of the Doctor and various companions in a plot to gain the immortality of Rassilon, the founder of Time Lord society, for himself. But it turns out to be a trap conceived of by Rassilon to deal with individuals with such a desire. As the First Doctor says in the end, "Immortality is a curse, not a blessing".
In the eponymous 1960s television series, Captain Scarlet was supposedly indestructible. In that series a Martian race known as the Mysterons have the ability to duplicate things which have been destroyed as they were when they were whole, including producing a living version of a dead person. Captain Scarlet is an agent of that race that has defected to fight against them but retains the ability to create a living version of himself after dying. The series uses the term retro-metabolism for this alien regeneration technique.
Jason Voorhees from the Friday the 13th movies is considered to be immortal. It is theorized that each time he is "killed" he is actually just put into a type of sleep while he regenerates enough of his lost and damaged tissue to function normally again. Jason has been killed- taking a large blade to the head-, but means outside his physical influence- a lightning-bolt struck a metal pole that had been rammed into his chest- led to his resurrection. When he was first killed, he survived permanent death via his father's wish that he would not be cremated, before his own murderer incidentally brought him back while trying to destroy his corpse, leading to a more unstoppable Jason. Jason even survives being blown up, by possessing other people and eventually being reborn through a dead relative. He also survives being blown apart in Jason X, although in this instance he is reconstructed as a cyborg through nanotechnology, suggesting that he will die if he sustains enough damage.
In the popular Japanese novel, Kōga Ninpōchō, the character Yakushiji Tenzen is considered immortal due to his ability to regenerate all damage done to him. How this regeneration is possible is differently explained in all of the different versions of the story.
In the TV series Heroes, the character of Claire Bennett- along with her uncle, Peter Petrelli, who has the ability to mimic the powers of others- has the power of spontaneous regeneration, resulting in her body tissue simply regenerating when she's injured. The one exception is that injuries to the brain will not regenerate immediately, but will instead induce an apparent-dead state. This is reversed after foreign objects are removed from the brain or spine. Adam Monroe, a character with similar powers, is also over 400 years old as a result of his ability, his cells dying and regenerating so rapidly his aging has been suspended. In the first episode of the third season, Sylar, the main villain in the show, acquires Claire's ability, but leaves Claire alive, stating that he is unable to kill Claire even if he wanted to, implying that she is truly immortal (Whether this means that Adam Monroe is equally unkillable remains to be seen).
In the television series Battlestar Galactica humanoid and raider cylon models download into new bodies if their current incarnation is destroyed. Their memories and consciousness are fully transferred to the appropriate model - be it one of 12 humanoid versions or into a new raider.
In the book Thursday's fictions by Richard James Allen, the character Thursday tries to cheat the cycle of reincarnation to achieve a form of serial immortality - by rediscovering who she is each time she comes back to life in a different body. Her actions create havoc for herself and all the characters in the story and when her son is offered eternal life at the end of the tale he turns it down in favor of living in the moment.
In the roleplaying game Wraith: The Oblivion, published by White Wolf Publishing, Inc., the afterlife is place known as the Underworld, where certain people who die enter as ghosts, emotionally bound to their former lives. Many are unhappy with their eternal existences and either become insane Spectres or ossify into statues. Originally, the Underworld was a place where the dead stayed until they reached transcendence, but the notion was later considered heretical by the Hierarchy.
In the game Soul Calibur III the final boss of the game Zasalamel (ultimate form “Abyss”) was a member of an ancient Egyptian tribe that guarded the mythical Soul Calibur. Being a genius among his tribe he mastered the forbidden art of reincarnation, so every time he would die he would be reincarnated. But every time he died began a fury of unimaginable and incomprehensible pain of his body and his soul until he was completely born again. After thousands upon thousands of years of being subjected to this pain he simply wanted to die. In a way he was actually forced to hate death through Pavlov’s theory of classical conditioning. Knowing that there he had gained so much power that he becomes even more powerful than the sword known as Soul Calibur and its evil counterpart Soul Edge, he formed a master plan that would lead to his death. Thus he gave the evil sword, Soul Edge, a body so that it could feast upon human souls until it was powerful enough to merge with Soul Calibur to break his curse.
One of the central concepts of the science fiction miniatures game Warhammer 40,000 is a place called the Warp. It is more officially called the Immaterium because it is a purely spiritual place that is dominated by thought and lacking the material nature of the real world. In the game it allows travel faster than light, but it is also a place where a mind can continue to exist after death. Alien races and gifted humans are even described as being able to return to life after death by manipulating the warp, especially the humans called Psykers and an alien the race called the Eldar.
DC Comics also has its fare share of immortals, such as the more advanced New Gods (e.g. Darkseid, Highfather),Vandal Savage, Superman (in some incarnations), Wonder Woman and the rest of the Amazonians, and the Guardians of the Universe. Also, long-time Batman villain Ra's al Ghul uses the Lazarus Pit to keep himself immortal.
Immortal Rain is a manga by Kaori Ozaki. The main character, Rain Jewlitt (nicknamed Methuselah,) was cursed by his friend Yuca with immortality. He is a kind, gentle man who loves people, and 600 years of painful memories can be too much. He can't stand watching the people around him die and attempts to separate himself from human connections. But when a young bounty hunter follows him, she saves him from his loneliness, and he saves her from hers. Though it's not really mentioned, the tragedy is that the young girl, Machika, will become an old woman and die in the blink of an eye (or she'll be killed young); he will be alone again, with the memory of her death haunting him forever. That is, unless he can become a human mortal again. Though the world is jealous of Methuselah's immortality, he suffers from it and wants nothing more than to die.
In the anime Bleach, several of the series' races are very long-lived in some fashion, though not explicitly immortal. A race of humans called bounts are effectively immortal so long as they can find human souls to devour. They are born like any ordinary human, but when they are around 20-30 years old, they stop aging. Hollows are likewise very long-lived, and subsist of the same methods as the bount. Deceased human spirits, be they shinigami or simply ordinary souls, age at an extremely slowed rate, such that those well over 2000 years old will appear at most to be in their eighties.
Naraku, the main antagonist of Inuyasha, became partially immortal when he rejected his human heart. He could not be killed unless his heart, which took the form of an infant called Akago, was destroyed. A good example of this is when Sesshomaru shreds Naraku to pieces (and yet he still survives) when they are fighting in the Netherworld, after Inuyasha destroys Naraku's barrier with Kongosoha (Diamond Shard Blast).
In Fullmetal Alchemist, immortality is partially achieved through the use of a Philosopher's Stone. By using energy stored in the stone (harvested from the lives of thousands of slain innocents), human souls can essentially leap from body to body (or, in some cases, inanimate objects), thus living on. However, doing so slowly destroys the soul until it can no longer support a new flesh-and-blood body, which quickly begins to rot as soon as it is taken over.
The Immortals of Highlander: The Series possess immortality granted by an unknown energy (called the Quickening), which is triggered by the trauma of a violent death. Once immortal, they can still be injured, but heal very quickly. Although there are discrepancies between the film and the series, the generally accepted canon is that they can die but will be healed and resurrected unless they are beheaded. If beheaded, usually by another Immortal during combat, the victor receives the loser's 'Quickening' or knowledge and power. Immortals can sense other Immortals by the 'buzz' they receive when near another Quickening. No Immortal will desecrate holy ground by battling on it. All Immortals are sterile. Their origins are mysterious, although it is indicated many of them are foundlings. The legend they follow says that when only a few remain standing, they will fight at "The Gathering" for something known only as "The Prize", which is the knowledge and power of every Immortal. It is unknown what power this will have on the very last Immortal, but the ending of the first movie suggests that The Prize is both an empathic link with all humanity and a restoration of the Immortal's mortality and fertility - the Immortal will be able to grow old, die of natural causes, and bear or conceive a child.
In Star Wars: Knights of the Old Republic II, Darth Sion has a unique force power called Pain, which keeps him alive forever but never allows any of his wounds to heal. The Exile convinced him to turn away from the Force which finally allowed him to die.
In Douglas Adams' novel Life, the Universe and Everything the character Wowbagger the Infinitely Prolonged had the misfortune of being immortal due to "a strange accident involving an irrational particle accelerator, a liquid lunch and a pair of rubber bands". After becoming immortal, he did everything one can do in life, several times, becoming terribly bored of everything due to him lacking the instinctive knowledge of other immortal beings that allowed them to cope with their immortality. He then made a plan that, despite being rather foolish, would at least keep him busy: he was going to insult, personally, all the living beings in the universe, in alphabetical order.
Naraku, the main antaganist of Inuyasha, became partially immortal when he rejected his human heart. He could not be killed unless his heart, which took the form of an infant called Akago, was destroyed. A good example of this is when Sesshomaru shreds Naraku to pieces (and yet he still survives) when they are fighting in the Netherworld, after Inuyasha destroys Naraku's barrier with Kongosoha (Diamond Shard Blast).
The Phantom is a comic character who appears to be immortal, fighting pirates and evil across centuries. However it is just a dynasty of heroes who pass the mask and suit of the Phantom along generations. Their secret is known just to their aides and wives.
In Andromeda, the character Trance Gemini is the avatar of the original Vedran sun, and as such, has special powers. She and her "sisters" can live as long as stars do: for billions of years. It's unknown whether Trance has physical immortality, or if she was even ever alive; it is alluded to on some occasions that she is dead and alive at the same time.
The character Oro in the Street Fighter metaverse is explicitly said to be immortal. M. Bison constantly claims to be immortal, but that is contradicted by Capcom's statement that he is dead and in Hell. There are also strong hints that Akuma and Twelve are immortal.
The nameless protagonist of the video game Planescape: Torment has a kind of limited immortality: he will die if injured enough, but he will always wake up again shortly afterward, albeit with some or all of his memories missing. This has led to a situation where, over thousands of years, different versions of the protagonist have existed, some good, some evil, and some absolutely insane. The goal of the game is to regain one's mortality and finally die permanently--a rather unconventional ending for a video game.
Several characters from the Sonic the Hedgehog series are immortal including Shadow the Hedgehog, Chaos and Black Doom. The most frequently recurring character, Shadow, is an artificial life form created aboard the Space Colony ARK that is explicitly declared 'immortal'. He was forced to witness the murder of Maria Robotnik, his best (and possibly only) friend, which creates a chasm between the other characters and himself and so has played antagonistic roles at times. However, neither Black Doom or Shadow are Invincible. It is implied that Shadow destroyed Black Doom in Shadow the Hedgehog, and Shadow himself was almost killed in Sonic Adventure 2; it is implied that he would have died if he wasn't rescued by Dr Eggman.
Poul Anderson's The Boat of a Million Years concerns several otherwise ordinary people who stop aging at maturity. The book follows their struggles through the millennia, through the late 20th century and beyond.
In the series of novels written by David Eddings, "The Belgariad" and "The Mallorean", the eight gods and their disciples, notably Belgarath and Polgara, are immortal.
In the Saw series, immortality is simply the passing of knowledge, or the continuing Jigsaw's work.