[[quoteright:300:[[TabletopGame/ChangelingTheLost http://static.tvtropes.org/pmwiki/pub/images/Changeling.jpeg]]]]
[-[[caption-width-right:300:You can't go home again if ''[[EvilTwin "you"]]'' never left.]]-]

->''"You say you don't have any objectives? That's tragic, you know, but you are still confused. The fact that you are empty means that you can fill that emptiness with as much as you want. You happy person, where's a better future than that?"''
--> -- '''Touko''', ''KaraNoKyoukai''

What defines "you"? The concept of identity, never mind [[TheHerosJourney the search for it]], is a complicated question that fiction tries to answer. Beware though, fiction likes to throw us curve balls.

Is it your memories? Those can be [[LaserGuidedAmnesia removed]] or [[FakeMemories altered.]] (Oh, are there [[EasyAmnesia ever]] so many [[ForgotTheCall ways]].) How about your personality? Well, that [[CharacterDevelopment changes over time naturally]] like it or not, but then again [[DeadPersonImpersonation you can play someone else]] and find [[BecomingTheMask you like being them better]]. Is it your body... or your [[WasOnceAMan humanity]]? Less luck there, if it isn't a [[FreakyFridayFlip body swap]] it's a [[GenderBender gender swap]] or [[WhatHaveIBecome something]] [[EmergencyTransformation much]] [[TransformationTrauma worse]]. Does the soul have anything to do with this? Are you still "you" if you reincarnate?

Then again, most of the previous changes are negative, but what about ''positive'' alterations? FlowersForAlgernonSyndrome and WhatMeasureIsANonSuper make you wonder just how valuable you are when you gain... or lose... faculties. TheMindIsAPlaythingOfTheBody, after all.

Don't let our meandering college philosophy depress you. After all, every non-nerve cell in your body is replaced in seven years (some die and get replaced, some go through mitosis and divide into two... wait, would that make those the same cell or two new ones? Does the original count as dead after that? Argh!), and change -- the evolution of a personality -- is natural. So you might as well wonder if you are the same "you" from five minutes, days, years, or decades ago.

Not to be confused with an AssimilationPlot, in which your identity is subsumed into a HiveMind. Compare SplitPersonalityMerge, where two personalities become one, and MentalFusion, where separate minds briefly become one. See also AmnesiacLover, who doesn't know how to love back after becoming an amnesiac. GrandTheftMe can happen if said identity was stolen. Living in a society where you can't have a real identity is IndividualityIsIllegal. See also QuestForIdentity. Compare LostInCharacter, where an actor becomes lost in a role.


* Carefully analyzed in ''Anime/MagicalGirlLyricalNanoha'', where the entirety of [[spoiler:Fate's DarkMagicalGirl]] role stems from being considered a mere tool by her "mother" and having the identity of her genuinely loved dead sister, to which her "mother" hates to no end.
* This is one of the central points in ''Anime/SerialExperimentsLain''. Lain is a painfully reclusive girl who barely speaks to anyone, but what about the Lain who spends every night drinking and hooking up at the clubs? Later, when some of TheMenInBlack are asking her some questions, she asks "Who are you?" They turn the question around, and ask her [[spoiler: when her father was born.]] She can't answer, because [[spoiler: her family is fake and she was never human in the first place]].
** This is also her source of angst in the final episode, when she wonders who she is after [[spoiler: erasing herself from everyone's memories, discarding her physical body, and altering history so she was never there]].
* The point of most {{Instrumentality}} plots - as seen on ''Anime/NeonGenesisEvangelion'' and ''Anime/YuGiOhGX'' among others - is to relieve humanity of the burden of isolation that comes with individual identities.
* A major theme of ''KaraNoKyoukai''. Shiki wakes up after a two year coma and is only able to feel " " - literally nothing, emptiness. She is unable to connect herself to the "her" from her memories, and no longer [[spoiler:has the "split personality" that she had been born with to keep her company]]. Her finding something to continue living for is a major issue for the rest of the series.
** Also done on a lesser scale with Tohko, who at one point [[spoiler:created an ''exact'' duplicate of her body, down to the last detail, which made her realize that her own individuality was completely meaningless, as that body could exist as her on its own. She links it to her consciousness and sets it to wake up the instant her current body dies, so it quite literally ''is'' her, complete with memories and everything]].
* In ''Anime/{{Monster}}'', the orphanage Kinderheim 511 existed solely to do this to children of criminals and political undesirables in East Germany. [[GoneHorriblyRight They bit off more than they could chew with Johan, though.]]
* A [[AlternateCharacterInterpretation darker take]] of [[Manga/RanmaOneHalf Ranma's]] situation could lead to this. Additionally, in an anime-exclusive episode, Ranma banged his head hard after being swatted into the Koi Pond, and was taken over by an [[IdentityAmnesia alternate personality]] that thought it truly was a girl, with almost insultingly stereotypical attitudes and tastes, in a situation that was one part this to one part LaserGuidedAmnesia. FridgeLogic on [[AndIMustScream what might be going on with Ranma's real personality]] while the "girly Ranma" is in control can be terrifying if you're a fan of Ranma...
* ''Manga/FullmetalAlchemist'': As Envy said, the tortured souls that compose his body perished a long time ago in mind and body. This may be true for all other souls that make up the Philospher's Stone.
** Al is also drawn into a HeroicBSOD by Barry by implying that his memories and body were just crafted by Ed.
** Happens for real with [[spoiler:Pride]], who loses his memories and personality, and assumes the role of [[spoiler:Selim Bradley]].
* Light's [[spoiler:MemoryGambit]] in ''Manga/DeathNote'' could be seen as an example of this- when he [[spoiler:[[LaserGuidedAmnesia relinquishes ownership of the Note]], he becomes a genuinely different, better person.]] Of course, it doesn't last.
** What he ''becomes'' is himself, minus all Kira-related CharacterDevelopment, but plus the character development of having encountered [[TheRival someone just as smart as himself]] (L ''may'' be smarter, but he handicaps himself with rules so it's hard to tell) and having something interesting going on in his life. Being totally selfish, he wouldn't have become Kira, gambling with his life and self, if he hadn't been bored to the depths of his soul, so there is a distinct difference even from the bright-eyed Light in the early chapters, let alone Kira at his height. Is this still 'him'? Maybe, maybe not. Hence all the questions at the top of the page.
* A possible outcome of repeating many {{Groundhog Day Loop}}s in the ''Franchise/WhenTheyCry'' multiverse. At best you come out insane.
* This is one of the driving forces of BlueDrop: Tenshi no Bokura. The protagonist's male best friend had his brain downloaded by aliens and copied into the body of a female alien, and his real body was cremated. Over the course of the series the copy- and thus the human and masculine identity- slowly fade away, leaving behind the [[BlueAndOrangeMorality most definitely not human]] original inhabitant of the body. Worst of all, the human identity doesn't fade away entirely, and by the end, the creature that is left is too human to retain its alien identity, and too [[BlueAndOrangeMorality alien]] to retain its human identity.
* This is an effect of the conditioning given to the cyborgs of ''GunslingerGirl'', where they are turned into blank slates who can be programmed to perform any function needed and it ensures loyalty to TheHandler. That's when it's deliberate, [[spoiler:like when Jose finally crumbles under all of the stress of the job and keeping up pretense with Henrietta that he TookALevelInJerkass and [[LaserGuidedAmnesia resets her with conditioning]] and use her to replace Beatrice, the unit's bomb-sniffing cyborg.]] This also happens to Angelica, whose faulty conditioning and implants causes her increasingly forgets things until her death.
** It also happens when the girls are first turned into cyborgs, as all of them are plucked from near death and it's best to condition over their mental trauma, although Rico still remembers what it's like before the Agency found her and Triela knows that she was found in Amsterdam.
* In ''SpiritedAway'', Yubaba binds people to her service by stealing their names and memories. Even Chihiro who was there for less than a day was already to beginning to forget her real name.
* In ''Manga/TheSecretAgreement'', while Kyuusai treats Yuuichi's blood finally awakening as the finding of an identity with the clan (which steals other people's life force in order to live), Yuuichi feels like his identity and all the meaning in his life has just been wrenched away. Particularly since it means his love for Iori is a delusion meant to enable Yuuichi to kill him, Yuuichi doesn't know how to navigate between what he thinks are real feelings and what his uncle says he must do.
* The driving force behind Kabuto's villainy in ''Manga/{{Naruto}}''. Kabuto was orphaned and suffered a head injury that robbed him of his memories at a young age, so he doesn't even know his original name or family. The Leaf village employed him as a spy, which meant subsiding his own personality into cover identities on a regular basis. Then he got brainwashed by Sasori and turned into a puppet. He was eventually freed by Orochimaru and found peace of mind acting as his second-in-command, but lost that after Orochimaru was killed. Kabuto eventually decided to focus on attaining power surpassing any other ninja in an attempt to bring meaning to his nameless existence.
** "Tobi" attempts to invoke this about himself, burying his old identity under layers of ObfuscatingStupidity and other lies. When it turns out he's neither the harmless goofball or the stoic Uchiha Madara, he claims that he doesn't ''have'' a real self and is just a vessel for his master plan. However this is simply how he runs away from his painful past rather than accept [[spoiler:that Rin willingly died to protect Konoha]].
* [[spoiler:Oz Vessalius]] from PandoraHearts suffered an identity crisis very early in life after [[spoiler:his father completely rejected him]]. Being the [[CheerfulChild type of]] [[StepfordSmiler person]] that he is, he ''was'' able to eventually bounce back from that blow, [[BrokenHero although not entirely]]. As of Retrace LXXIV, however, [[spoiler:he seems to have lost his sense of purpose as well as any semblance of self-worth, all of which is the result of [[BreakTheCutie everything]] that [[MagnificentBastard Jack]] [[BreakThemByTalking did]] to him in the previous chapters.]]
* Sasami of ''TenchiMuyo'' had this. After a major fall when Ryoko invaded Jurai, she was rescued by Tsunami and bonded with her. For over 700 years, she wanted to tell someone the truth, that she was nothing more than a vessel and that the real Sasami was dead, but always stopped because she was afraid that if she did, they'd abandon her. Thanks to a mistake on her part, the others learn the truth, but quickly reassure her that they'd still love her. However, when Sasami passes out from all of the excitement does Tsunami reveal the truth - she never died that day. The trauma from the fall and rescue caused her to think that. She reassures everyone that when Sasami's older and can handle the truth, she'll learn it.
* In ''Manga/OnePiece'', on the island of Dressrosa [[spoiler:the sentient toys were once humans transformed into toy creatures by a Devil Fruit power. It seems a majority of those close to the transformed victims not only don't recognize the victim they ''forget the person even existed.'']]
* In ''Manga/NobunagaNoChef'', the title chef, Ken, [[TheAce has extensive knowledge of high-class cuisine and Japanese military history]] so he knows what foods he can and can't make, the outcomes of battles, who his boss Oda Nobunaga is and how he (Oda) will die -- and that's it. He lost his memory when he "fell" into the past and the only other person who might know ("Ken! You must return to the Heisei era!") is killed. He gets the occasional flashback but these aren't terribly helpful since he doesn't remember [[spoiler: who that guy was who taught him military history as a boy and what a buffet is]].

[[folder:Comic Books]]
* ''{{Superman}}'' #296-299 had a storyline where Superman finds himself powerless as Clark Kent and spent most of it sticking to one identity while trying not to fall back on the other. In the end, he had come to a realization:
-->'''Superman:''' I tried to decide whether '''Clark''' or '''Superman''' is more important...and realized that to do away with '''one''' would be to '''kill''' half of myself--'''whoever''' I really am! So even '''before''' I got rid of my power problem, I'd decided...meek, mild-mannered '''Clark Kent''' will still walk the streets of the city, while up in the sky...the world will still watch and thrill to the sight of--'''A JOB FOR SUPERMAN!'''
* In Alan Moore's ''{{ComicBook/Miracleman}}'' Michael Moran often feels pathetic in comparison to his alternate form/second personality, the titular Miracleman. Over time he gets less and less time to spend as himself, creating the sense that Miracleman is slowly and inadvertently taking over their body. [[spoiler: In the end, Michael realizes that this is exactly what's happening and than proceeds to write up what is essentially a suicide note. He than walks to a nearby secluded hilltop and tearfully says his transformation word one last time; when the transformation happens, Michael is gone forever and Miracleman never returns to his mortal form again.]]

[[folder:Fan Works]]
* While KnightsOfTheOldRepublic fanfic adores this trope, the Brotherhood of Shadow fan-made expansion pack cranks it UpToEleven with virtually ''every'' major character abandoning, obliterating, and adopting new identities. A Twi'lek named Channa Mae was found by Jedi Master Solomon, who nicknamed her "Matilda." When the Mandalorian Wars came, Channa Mae abandoned Solomon and the Jedi, as well as the nickname, to fight for Revan's cause. After the war, she abandoned even the Channa Mae identity to become "Shadow," Revan's assassin/aide/secret apprentice. [[spoiler: When Revan "died," Shadow found her Force connection severed and became Sera Degana, a crewman on a smuggling vessel. But, then Revan and Solomon come back into her life...]] Another example is Kobayashi, [[spoiler: who was once a Jedi apprentice, and lost his own Force connection after his master was killed]], then took on a new identity as a scout and smuggler. Solomon also abandons ''his'' identity [[spoiler: after being critically wounded and thought dead on Taris. His goal is to kill Revan - and Shadow - to avenge his former Padawan and his niece (who Channa had to kill in self-defense)]]. The Brotherhood of Shadow itself cements it all - they were an elite Sith order who were critical in repelling the Rakatan invasion of their world, seeing themselves as a single unit, not as individuals. [[spoiler: When the first Sith Lords betrayed them, the entire Brotherhood was locked in a mind-trap. Over the millennia, they truly did become a single mind - one looking for a host]].
* [[TheMedic Glory]] suffers this in ''Fanfic/FalloutEquestriaProjectHorizons'' when the Killing Joke (not the [[ComicBook/TheKillingJoke comic book]], but a virulent, mutated, radioactive strain of [[Recap/MyLittlePonyFriendshipIsMagicS1E9BridleGossip Poison Joke]]) transforms her into a clone of Rainbow Dash. She finds herself losing most of her intelligence as Dash's harebrained adrenaline junkie personality overwrites her own calm, rational, intellectual one. And to make things worse, Rainbow Dash was her civilization's equivalent of [[Literature/NineteenEightyFour Emmanuel Goldstein.]]
* In ''FanFic/MegaManDefenderOfTheHumanRace'', sometimes Mega Man is so busy being Mega Man that he forgets he can be Rock.

* ''Film/DarkCity'' goes hog-wild with this trope. Every resident in the city (except Dr. Schreber, and even he's not truly spared) is not who they think they are. Every night, The Strangers will go in and mix up a new batch of memories for every person in The City. There is no telling how many years this is going on, and it's highly unlikely that there's any copies of each person's ''original'' memories, and thus personality.
** TheHero's refusal of the serial killer identity becomes a major plot point because [[spoiler:The City was set up to determine whether memories were the deciding factor. Now that they have proof that they weren't, they can shut it down for good.]]
** While humans seem to subvert this trope, retaining aspects of their personality even after their memories have been changed, the Strangers seem to play it straight. When Mr. Hand takes on the serial killer memories Murdoch was ''supposed'' to have, it really does change him into a monster.
* The 1996 movie adaptation of ''Film/{{Casper}}'' expanded Casper's backstory, which involved him slowly losing his memories of his former life when he became a ghost. He does have recollections when he finds his old toy room, but it might just be a matter of time until he forgets who he is again. The idea of ghosts losing the identities of their living selves also becomes a tearjerker when Kat's father turns into a ghost and cannot remember who his own daughter was before he was resurrected in the Lazarus machine.
* In the scifi film Eleven, by Makodap, the main character Pete Baxter attempts to leave a future hotel without paying his bill. Before he can leave, a woman called miss Stevens gives him a gift of scotch, upon drinking it and phoning for call girl, Pete is [[PainfulTransformation transformed]] into the woman he ordered, and slowly starts to loose his mind, becomming her mentally.
* This is the crux for much of the drama in ''Regarding Henry'', starring Creator/HarrisonFord. In it, the title character [[TisOnlyABulletInTheBrain survives a gunshot wound to the head]], only for the resulting pinched artery to affect his memory. Cue the rest of the movie depicting him [[QuestForIdentity coming to terms]] with [[LossOfIdentity not remembering anything]] about [[MissingTime his life before]] the [[TraumaInducedAmnesia shot]].
* This is a major theme of ''Film/NeTeRetournePas'' ("Don't Look Back"), as growing inconsistencies between Jeanne's memories and reality cause her to start question who she really is and how many of her memories are actually real.
* The movie ''Film/TheWall'' for the Music/PinkFloyd album ''Music/TheWall'', shows this symbolically. If you see a group of people wearing masks, such as on the train during "Another Brick In The Wall Part 2", or during the rally in "Run Like Hell", then this is what it means.

* Dementors essentially do this to their victims in ''Literature/HarryPotter'' - just being near them for a few minutes is enough to [[EmotionEater drain the happiness out of you]], and prolonged exposure leads to depression and the loss of will to live. Receiving a Dementor's "kiss", which steals your soul and leaves you with no sense of self at all, is seen as a FateWorseThanDeath.
** Memory charms are also a means of rewriting a person's memories, and thus (in extreme cases) creating new identities for them.
* Intercision in ''HisDarkMaterials'' separates a person from their daemon. At best this means they become incurious and weak-willed, at worst it means they hang around ghoulishly and then die.
* 1930s pulp hero DocSavage maintained a secret installation where he used brain surgery and memory modification to 'cure' captured villains' criminal tendencies and turn them into productive members of society -- practices that would be considered torture and brainwashing [[ValuesDissonance nowadays]].
* In ''Literature/TheDemolishedMan'', [[spoiler:The reader only at the end discovers that "Demolition", the punishment for murder, is the erasing of all your memories. This is because they feel that anyone who flouts the system has the drive society needs, but obviously they don't want murderers running around. So your memories are erased and you can become a productive member of society]].
* ''The Second Trip'' is about a new person, who was a criminal who had his memory erased and a new personality implanted in him. It is his "second trip" in life.
* This is the most important theme of Robert Bolt's play ''AManForAllSeasons''. In his introduction to the play, Bolt explains how taking an oath is committing one's whole ''self'' to the statement. A man can lose his family, his job, and his wealth, but if he is willing to draw a line in the sand and say "I will ''not'' do this thing, under any circumstances", then he probably has a clear sense of who he is.
--> '''Thomas More''': When a man takes an oath, he is holding his own ''self'' in his hands. Like water. [''Cups hands''] And if he opens his fingers ''then''-- he needn't hope to find himself again.
* One of the major characters in ''[[Literature/KnownSpace The World of Ptavvs]]'' is a telepath who seeks to understand aliens by absorbing their memories and worldviews, which become just as "real" to him as his own. Only the fact that he's still in his own body allows him to know which memories are his. Then he absorbs memories from another telepath, an alien who has much more experience with other species than he does, and spends most of the book identifying as and acting like that alien--first thinking he was somehow switched into another body, then being unable to emotionally accept that he's really an [[PunyEarthlings inferior human]] rather than an advanced alien. [[spoiler:He snaps out of it when he discovers that he needn't feel inferior--the alien is actually incredibly stupid]].
* [[spoiler:Lieutenant Tisarwat]] in ''Ancillary Sword'' must rebuild her personality and sense of self after [[spoiler:the ancillary implants connecting her to [[HiveMind Anaander Mianaai]] are removed]].
* ''Memory'' by Linda Nagata explicitly answers one of the above questions: if you reincarnate, you're not really the you that you once were. You have the same [[OneTruePairing soulmate]] (of whom there's one and only one [[StrangledByTheRedString even if you can't stand each other]]), and you're likely to retain some old skills without any idea of how you learned them, but you can change your identity for better or worse, pulling yourself back from the MoralEventHorizon or dropping down into it.
* In JohnCWright's ''[[Literature/TheGoldenOecumene The Golden Age]]'', Phaethon is suing for his father Helion to be declared dead, because the current Helion was resurrected from a recording an hour before the last version died. Helion repeatedly tries to reconstruct his last hour so he can figure out what he was thinking. What deeply disturbs Helion is not so much the possibility of being declared dead with his son inheriting all as the possibility that he really isn't the real Helion. [[spoiler:In ''The Golden Transcendence'', Daphne reveals to him the secret he was missing to reconstruct himself, and that he could not reconstruct it because he was afraid of losing his identity, when his last version had [[HeroicSacrifice willingly lost his identity and life]]. After the Transcendence, a [[ItWasAGift gift]] is given to Helion: a priority routine to transmit his information, so that the last thing to be transmitted will be his fear of losing himself and another such resurrection will not trouble him.]]
* ''[[OrsonScottCard The Worthing Saga]]'' explores this trope in quite some depth as it relates to memory. Every time someone enters [[HumanPopsicle suspended animation]], their memories are completely wiped from their brain, and must be restored from a recording. Such recordings are rather fragile, and if yours breaks, you'd best restart your life from the beginning and relearn what you've forgotten, as trying to live with someone else's memories, knowing that they made choices that your instincts tell you are wrong, tends to cause insanity.
** The setting also has telepaths, who're subject to a lesser version of this trope. The memories of other people are just as real to them as their own, and if they happen to [[AMindIsATerribleThingToRead find a memory they'd rather not have]], too bad--it's a part of them forever. The knowledge that they're still themselves tends to ward off insanity, though.
** One story in the setting, ''Lifeloop'', deals with this trope from an entirely different direction: the relationship between actors and their roles. The main character acts in real-time, unscripted porn films that are filmed over the course of several days, and has learned to fit herself perfectly to her roles. The actor she's matched with for one assignment breaks the fourth wall and confesses that he loves her, not the character she's playing. She goes along, improvising with him, but completely fails to realize that he isn't acting as well.
* In the XWingSeries, there is a DeepCoverAgent named Gara Petothel who was trained from an early age to create a personality and a life, fully immerse herself in it, complete objectives including forming and betraying the closest of connections, and shed it without a qualm. To the point where later she can't even remember if her previous identities had friends and interests. At some point the handler who saw her between missions died before she came back into a splinter of Imperial service. There Gara became disgusted with her commanding officer's [[WeHaveReserves handling of his crew]] and arranged for his escape craft to be spotted by New Republic forces, then assumed a new identity and waited to be contacted, getting put into a New Republic fighter squadron. But something was different this time - she was affected by the PowerOfTrust and genuinely [[ReverseMole defected.]] She tried to throw away who she'd been and just be Lara Notsil, pilot, but [[ResignationsNotAccepted she couldn't]], and eventually her past came crashing in on her.
---> "All the furniture that made up the way I'd thought and felt about things all my life started coming loose in my head. Nowadays it slides around and breaks into pieces and I have no idea what parts of it are real and what aren't. It hurts, and a lot of the time I don't know who I am anymore."
** Then things got complicated.
* Creator/MikeResnick's short story "Me and My Shadow" posits a world akin to that in ''The Demolished Man'', where convicted criminals are "erased" and given benign personalities. The narrator is one of these--except for the part where he still has a little voice in his head that tells him to kill people. And his new personality as an accountant is meticulous enough to make sure that this time, he won't get caught...
* Happens in the sci-fi novel ''The Lord Of The World'' by Russian author Alexander Belyaev. Ludwig Stirner, after realising that he cannot go on with his plans, [[spoiler:releases Elza from the thoughts and feelings he programmed in her mind and apologizes to her]]. Finally, he decides the best way to deal with himself is [[spoiler:to use his own machine against his mind to create a new identity, locking his true self deep within his subconsciousness, thus "ending Stirner's life" as he put it]].
* In ''[[Literature/{{Ringworld}} The Ringworld Engineers]]'', Nessus gains leverage over Chmeee by dosing him with (hitherto unknown) Kzinti [[{{Immortality}} boosterspice]]. Because he is now younger and scar-free, he would lose his rather comfortable identity in Kzinti society unless he is provided with evidence to support his story.
** Chmeee also considers his scars to be part of his personal identity as a warrior, and the loss of them to be almost like [[EveryScarHasAStory losing his memories of the fights where he got them]].
* After spending eighteen years near-catatonic due to losing the ability to feel positive emotions, the protagonist of Greg Egan's short story "Reasons to be Cheerful" undergoes a neurological experiment that gives him the capacity to consciously choose to enjoy or not enjoy things. Cue ([[{{Wangst}} w]])angst over the fact that all his preferences are artificial, eventually leavened by the conclusion that everyone else' preferences are artificial too, and he's just more aware of it.
* In JohnCWright's ''[[Literature/CountToTheEschaton Count To A Trillion]]'', the princess's revelations leave Menelaus wondering who he is.
* In ''The Wereling Trilogy'', most people who are turned into werewolves become violent and no longer identify with other humans.
* Several characters in ''ASongOfIceAndFire'' go through this.
** [[spoiler: Arya Stark]] ends up joining "The Faceless Men" a guild of assassins that trains all its members to become 'no-one'. On the outside she claims it, but on the inside she struggles to let go of her previous identity.
** [[spoiler: Sansa Stark]] lives under a pseudonym as 'Alayne Stone', [[spoiler: Littlefinger's bastard daughter]], and starts thinking of herself as Alayne rather than [[spoiler: Sansa.]]
** [[spoiler: Theon Greyjoy]] is tortured until he forgets his previous identity, instead taking on the identity of 'Reek'. He struggles between the two identities, but eventually regains his original identity.
* In AndreNorton's ''[[Literature/{{Warlock}} Forerunner Foray]]'', Ziantha faces "erasure" if the Patrol catches her.
* Features heavily in [[Literature/TheHungerGames Mockingjay]] with [[spoiler:Peeta Mellark]]. The character in question is tortured, brainwashed and turned into a weapon against the rebellion in general and Katniss in particular. Katniss [[spoiler:realizes that she's lost the Peeta she knew and had fallen in love with even though he's physically still alive. Lucky for her he eventually gets better.]]
* Tahiri in the ''Literature/NewJediOrder'' fears that this will happen to her after some [[MadScientist Shapers]] partially turn her into a [[ScaryDogmaticAliens Yuuzhan Vong]], especially when she realizes she sometimes ''thinks'' in the Yuuzhan Vong language, and it gets even worse later when her Vong side morphs into a full-fledged EnemyWithin. She ends up resolving the issue via SplitPersonalityMerge, essentially creating a ''third'' identity combining the best elements of both.
* WilliamGibson in {{Neuromancer}} provides the example of Armitage / Corto. Corto begins as part of a US operation in Russia, but is betrayed by the US, mauled by air defenses, and later made to testify falsely by his superiors. Soon after, he disappears into the criminal underworld and emerges as Armitage, a man who literally sits in his hotel room staring at the floor when not working. It's a JustifiedTrope, since [[spoiler: a rogue AI brainwashed Corto into becoming Armitage, and it eventually unravels spectacularly.]]
* In ''Literature/ThoseThatWake'''s sequel, Laura feels ''empty'' after losing her memories of the first book and Mal, and has no idea why because she can't remember--but she feels very strongly that her "normal" life is like a dream.
* In ''Literature/{{Pact}}'', Padraic, an exiled [[TheFairFolk faerie]], tricks novice practitioner Maggie Holt into giving him her name, taking with it her identity. Padraic becomes Maggie Holt, and recognizable as such to everyone that Maggie knows, while Maggie becomes the nameless girl in the checkered scarf, slowly falling apart spiritually without the name that is the center of her being.
* In ''Jackrabbit Messiah'' by Geoph Essex, the [[CharacterTitle title character]] has [[{{Understatement}} a bit of trouble]] staying in one place, to the point of ''losing his own sense of self'' when his [[spoiler: [[SecurityBlanket iconic costume]]]] is taken away. Even his [[HelpfulHallucination hallucinatory best friend]] will disappear when this happens, leaving him completely without any link to his own identity.

[[folder:Live Action TV]]
* Death of personality has replaced capital punishment in ''Series/BabylonFive''. A machine [[LaserGuidedAmnesia wipes the personality and memory]] of a murderer and [[FakeMemories replaces them with a new set]], letting them live out a life of willing hard community service [[ConvenientlyUnverifiableCoverStory with an assumed identity]] [[TomatoInTheMirror without them ever being the wiser.]] A telepath is present to perform scans before and after, so as to ascertain that the process has worked, but does not carry it out themself.
** The [[spoiler:Vorlons and the Shadows]] leave the galaxy when they are asked their own [[ArmorPiercingQuestion Armor Piercing Questions]] and they realize they don't have answers to them anymore.
* ''Series/DoctorWho'': The Doctor's ability to [[TheNthDoctor regenerate]] is an interesting twist on this: the many incarnations of the Doctor have entirely different looks and personalities, yet they somehow remain fundamentally the same character.
** Lampshaded [[TearJerker heartbreakingly]] by the Tenth Doctor, who viewed each regeneration as the death of his current self.
** Also explored in the "Human Nature"/"The Family of Blood" two-parter, where the Doctor's MemoryGambit creates a completely new and separate "John Smith" identity with his own personality and memories, who is ''terrified'' at the idea that restoring the Doctor's memories will kill him. Seems like a reasonable reaction to realizing your entire life is a lie and you were invented on a whim by an unstoppable alien mastermind, frankly.
** In the episode "A Christmas Carol", the [[TheScrooge antagonist]] has a MacGuffin device with isomorphic controls which only he can operate, and he is unwilling to help save a crashing space ship. The Doctor meddles with his past, changing his memories and character in the process. When he finally succeeds in changing him to someone willing to help, the controls no longer respond because they no longer recognize him as the same person.
** Also seen in what happens to victims of Cyber-conversion. The memories remain, but what this form (called "Human.2" by the Cybermen) lacks is emotions and a true understanding of what happened to them. It has been seen that those Cybermen who are made to realize the truth generally blow up, as they cannot live in that form.
* In a different vein, the TV series ''NowhereMan'' had as its title character a man whose existence has been erased.
* Creator/JossWhedon:
** He begun to explore the effects of complete mental reprogramming in ''Series/{{Dollhouse}}''.
** It also happened on ''Series/{{Angel}}'' when he wiped Connor's mind and gave him different memories, changing reality so that he was happy and well-adjusted. And apparently, gave some fairly specific instructions on what he wanted his new personality to be like.
* An unintentional (... probably) side effect of the Wraith retrovirus in ''Series/StargateAtlantis'', at least until one of its more notable victims got his hands on it.
* Done in a rather heavy-handed way on ''Series/{{Heroes}}'', in the episode "I Am Sylar".
** More is sure to come in volume 5 once [[spoiler: "Nathan" cottons on to the truth]].
* ''CriminalMinds'' dealt with this in "Tabula Rasa": a serial killer awakens from a three-year coma with total retrograde amnesia. The BAU tried to prove him guilty, but a couple of them raise the point that even if they did prove that the man named Brian Matlof was responsible for the murderers, the Brian Matlof sitting in court could be argued to be a different person. Eventually [[spoiler: his memories return, and he escapes, returning to one of the bodies to verify his own memories. When the BAU arrive, he threatens to kill himself, believing that he'll get the death penalty anyway, but Hotch says "if you really believe that you're a different person, prove it. Do the right thing", and Matlof decides to plead guilty instead, avoiding the death penalty]].
* In ''Series/BattlestarGalacticaReimagined'' a number of characters suffer identity crises of various types. The Eights get the worst of this: Boomer [[spoiler: almost shoots herself]] because she 'doesn't know who she is anymore'. She [[spoiler: and other 'sleeper' cylons]] have serious identity crises when they [[spoiler: discover that they've been cylons the entire time]] and that [[spoiler: all their memories are falsehoods implanted by Cavil or other cylons.]]

* {{Supertramp}}'s "The Logical Song":
-->''"Please, please tell me what we've learned''
-->''I know it sounds absurd''
-->''Please tell me who I am."''
* This [[CreatorThumbprint pops up quite a bit]] in Music/DavidByrne's lyrics.
** "Somebody":
-->Somebody, somebody took away our name.\\
Somebody, somebody tell me who I am.
** "Angels":
-->I can barely touch my own self. How could I touch someone else?\\
I am just an advertisement for a version of myself.

* A related philosophical question is called "The Ship of Theseus": if each plank in the ship is replaced when it starts to rot, and over time one-by-one every single plank is replaced, at what point (if ever) does it stop being the same ship?
** The Ship of Theseus is also known as George Washington's axe (my grandpa replaced the handle, and my father replaced the head).
*** There's a Kerryman joke to that effect: a Kerryman boasts that he's had the same axe for the past fifty years - with the handle and head replaced, respectively, five and eight times.
** Specifically, this trope is about the [[ContemplateOurNavels philosophical problem]] of [[http://en.wikipedia.org/wiki/Personal_identity_%28philosophy%29 personal identity]]. The general notion is that people stay more or less the same throughout their lives, ''despite'' changes to their bodies (if these changes do not drastically change the way the body functions). Just ''what'' makes several iterations the same person, is central to the debate. The debate itself is notorious for the heavy use of [[AppliedPhlebotinum science-fiction]] examples, such as:
*** [[TeleportersAndTransporters Teletransportation]]: if a [[Franchise/StarTrek teleporter]] dematerialises you and reconstructs you elsewhere, are the iterations the same person? What if the original is never deconstructed, but a [[AlternateSelf duplicate]] is made?
*** [[BrainInAJar Brain]] and/or [[FreakyFridayFlip mind]]-transplants: are you still the same person when you have a completely different body?
** Not so much Philosophy but a real life example that I personally believe answers this question somewhat, in "Peopleware" a book about managing programmers a case study was made of "the black team". The black team had a strong cultural identity that survived after every original member had left. The second generation picked it up from the first, the third picked it up from the second.
** Hey, this was used in ''Discworld/TheFifthElephant'' with the hereditary axe. Sometimes the handle needs to be replaced, sometimes the head, but it's still the hereditary axe.
*** And what if the old head, rather than being thrown out entirely, is reforged into a new head for a new axe? Is that ''also'' the hereditary axe?
** Keep in mind this also applies to people. Your entire body is completely replaced once per decade, give or take.
*** In addition, our particles are in constant flux. On the lowest observable levels, we aren't the same from one ''nanosecond'' to the next.
*** Even with the cells that stick around for a few years, the atoms that make up the cell won't be the same from one month to the next. Your entire body is only a channel for matter, all the atoms in your body won't be there within a few months, and as creepy as it is a lot of them will probably be in other peoples bodies and vice versa.
*** But keep in mind (no pun intended) that essentially going down to the molecular level all that makes you "you" is your DNA, the genetic blueprints and instructions stored within your cells. Individual atoms are not any different from each other, able to give perfect transfers of kinetic energy during collisions. The only means of differentiation at that level is the way the atoms assemble; that is what makes you "you".
*** This isn't quite the case - epigenetics is a massive field of things necessary for DNA alone to create a functional cell, and environmental effects always affect the organism during development. Case in point, picture how a fetus develops differently if the mother drinks heavily during pregnancy. Or if she's undernourished, lacks critical vitamins, or any of the other horrible things that can happen to you long after sperm and egg meet.
*** In ''Literature/TheWonderfulWizardOfOz'' the Tin Woodman got his body replaced one piece at a time, including his head, when his enchanted axe cut it off. But since it was one piece at a time and not all at once, "he" is still Nick Chopper (his name pre-tinning) rather than some entirely new being.
**** On the other hand, in ''The Tin Woodman of Oz,'' the Tin Woodman meets his former head in a cupboard of the smith who made his tin body, and they have a not-very-interesting (or friendly) conversation. Who is the real Nick Chopper?
*** In a gross oversimplification hindered by linguistic equivocations, traditions descended from the Vedas such as Buddhism, Taoism, and Hinduism solve this problem by seeing self not as a permanent thing, but more like a moving wave. How can it be the same wave when no molecule of water is a part of it for long? Simple: the wave is ''organized motion through time.'' Self is usually described as unreal, but best viewed as action-through-time. A deeper discussion of this would probably be way past the scope of this page.
** Creator/DouglasAdams struggled with this when he visited Japan during ''Last Chance to See'' and notes that an important historical building looks far too new. A local explains that the original burnt down, and was rebuilt from all new materials (and not for the first time). Adams asks how it's even the same building, and is told "It's always the same building" as if the question is crazy. He concludes that ''someone'' is missing the point, but that it may well be him.
* A crucial part of TheHerosJourney, frequently manifested in the BellyOfTheWhale.
* TruthInTelevision: Lobotomies, a surgical procedure where the frontal lobes are removed (or a few vital areas are sliced), essentially destroying the personality of the individual concerned.
** [[http://en.wikipedia.org/wiki/Phineas_Gage Phineas Gage]]
** It seems to depend. During the period where lobotomies were a popular treatment for troubled teens, a "doctor" developed the non-skull-breaking technique of sticking a thin rod ''[[EyeScream through the eye socket]]'', swerving around the eyeball, and stirring it around in the frontal lobe. There's a picture of said doctor merrily doing this to two patients at once. Results varied wildly. Some people hardly seemed affected at all, aside from being very pissed about it. Brains are complicated things that can form new connections to make up for some damage. That's how despite losing brain cells every year, humans don't peak in intelligence at twenty-five and get stupider from that point on. Brain cells can take up a lot of slack.
** Lobotomies, in their original form, certainly have a well-deserved reputation for being dangerous and damaging the subject's personality, but modern developments (such as the cingulotomy) are apparently far less so, and can be far more successful in alleviating mental disorders without disrupting an individual's personality. The book ''Opening Skinner's Box'' by Lauren Slater devoted a chapter to psychosurgery where she pointed out that cingulotomy surgery tends to be much more effective than conventional psychopharmocological drugs in treating long-lasting mental disorders, but the former is still stigmatized as highly unsafe and invasive, so surgery is rarely carried out. In the US, an individual with severe mental disabilities must demonstrate that a large variety of drugs have had no effect in alleviating their suffering before a cingulotomy will be considered.
* There's also ''The Myth of Fingerprints'', where fingerprints from say 8 years ago are identified as Alice, but since the entire body regenerates it's not really the same person after enough time passes. Even brain & nerve cells do replace themselves, but they do it so slowly that the effect is negligible, which is why it took so long for scientists to notice.
** That logic was played with by Terry Pratchett in one of the ''Discworld'' books. Sgt. Colon, in an attempt to look somewhat more intelligent, makes the 7 years comment. Nobby then raises the tattoo question. Fred's response is that those cells came from other people's tattoos, which might qualify as fridge squick[[note]]In reality tattoos are in the skin rather than on it, and as cells in the skin weaken and are replaced, they come apart and get cannibalized for parts. If that doesn't happen, they undergo mitosis and divide into two cells, genetically "you" but not the same cell as before. Ink stays in that layer. Tattoos do not cause "ink cells" to form[[/note]]. Colon, at least, is excused for ignorance.
* Query: if the nerves connecting the two lobes of the brain are cut, what happens to the self, or the sense of self? What happens to "I"?
** Very little, as it turns out. [[http://en.wikipedia.org/wiki/Corpus_callosotomy Corpus callosotomies]] are rarely but regularly performed to alleviate severe epilepsy. Speech and memory are affected some, but the sense of self is usually entirely intact.

* In the AudioPlay/BigFinishDoctorWho episode "[[Recap/BigFinishDoctorWho054TheNaturalHistoryOfFear The Natural History of Fear]]", the setting is a Creator/GeorgeOrwell style {{dystopia}}. The state Editor, who's in charge of "revision", has the Doctor's voice, but he acts like a completely different person. When it's revealed that "revision" is pretty much an irreversible lobotomy followed by a brand new personality implant, we get some idea of what may have happened to him and his companions... to add to the MindScrew, it's the only Creator/BigFinish episode that has only a cast list instead of a proper credits list.

* According to reincarnation doctrine, deceased souls are brought back to life in another body... but that doesn't mean they come back as a whole person or animal with any memories intact.
** The Dalai Lama is found each time by placing a young child in front of a wide selection of toys; he'll play with the same ones every time. So something is kept intact (then again, the Lama is said to be able to willingly decide if he reincarnates or not, so there's a belief that he has more control over this than a more less enlightened person).

[[folder:Tabletop RPG]]
* In TabletopGame/DungeonsAndDragons, getting bitten by an Ophidian (snake-like creatures commonly found as slaves of the evil serpentine Yuan-ti) results in a not-so-pretty transformation process. After two weeks, the victim fully transforms into another Ophidian, with no memory of its previous existence.
** Similarly, a Mind Flayer larva devours the brain of a host humanoid, and absorbs the host body as part of its own, in a process called ceremorphosis. The newborn creature has no memory of its host's existence. However, mind flayers scare other mind flayers with stories of the Adversary, a mind flayer who retained its host's personality and, in revenge, dedicated itself to destroying mind flayer society from the inside.
** Also true of some varieties of slaad (embodiments of ChaoticNeutral), of bodaks (featureless beings similar to but distinct from doppelgangers), and of many varieties of undead. This seems to be associated with magical creatures that are either evil, or so chaotic as to be completely beyond conventional morality.
** When dealing with undead, it tends to vary depending on the type. A mindless undead like a zombie is just an empty body, and with the proper magic a person could be resurrected with a new body that exists alongside the zombie, since the soul left the body upon death. A vampire on the other hand must be slain to bring back the person - the vampire has the memories and personality of the original, but is twisted into evil and the person brought back will be the original again.
* The TabletopGame/NewWorldOfDarkness uses this often as an example of what happens when your KarmaMeter bottoms out.
** ''TabletopGame/VampireTheRequiem'' -- hit Humanity 0 and your [[EnemyWithin Beast]] takes over, reducing you to a predatory draugr that cares only about feeding.
** ''TabletopGame/WerewolfTheForsaken'' -- hit Harmony 0 and the human half of your spirit decays entirely as some other type of spirit fills the gap, turning you into a ''zi'ir''.
** ''TabletopGame/ChangelingTheLost'' -- hit Clarity 0 and you disappear into anything from constant hallucination to utter catatonia [[spoiler: and if you do it when you're Wyrd 10, you become one of the [[TheFairFolk Gentry]].]]
*** Also, this game takes the trope much more literally, as the page image implies; the vast majority of changelings can't return to their former existences because they have literally ''lost their identities'', as the Gentry create [[EvilTwin Fetches]], magic-spawned {{Artificial Human}}s, to adopt the lives of those they take as slaves. As a result, the changelings find their old identity has been taken from them, so they are forced to make new lives for themselves. Well, that, or [[MurderIsTheBestSolution try and kill the Fetch to steal their identity back]]...
** ''TabletopGame/GeistTheSinEaters'' -- hit Synergy 0 and your soul departs entirely, leaving your [[OurGhostsAreDifferent geist]] to use your body as a flesh puppet to fulfill its strange desires.
** ''TabletopGame/MummyTheCurse'' plays around with it; whereas the default for most supernaturals is Morality 7, most Arisen rise from their slumbers with Memory 3, meaning they're little more than divine murder machines in service to the Judges. It's only as they remain awake that they start remembering who they were over the years... only to have to face the possibility of forgetting it all ''again'' with the inevitable return to the tomb.
* In ''TabletopGame/{{Nobilis}}'', the lifepath example in ''Antithesis 1i'' features a girl who nobody listened to, who found that people ''would'' listen if she repeated the sounds made by the local environment. So she kept doing so, until one day, she realised she no longer knew who she was or what she would say - she had become nothing but the voice of Morrowen Hollow. And then the Voice, the pattern of sound, took on a life of its own.
* TabletopGame/UnknownArmies features a SanityMeter with five separate variables. Self represents approaching this trope from one of two ways - either losing yourself in utter cynicism until you'd betray your old ideas ("Getting hardened,") or else taking so many blows to your sense of self you are just a wreck ("failed checks.") In either case, maxing out either end of this meter means there's virtually no "you" left in there.

* In ''{{Bionicle}}'', the plan of the BigBad Makuta Teridax involved trapping the entire Matoran population of Metru Nui into metal spheres, which, over time, deteriorated their physical bodies and wiped their memories clean. The Turaga elders had to reteach everything to them, however one Matoran, Ahkmou, accidentally ended up with Teridax himself, who proceeded to forge a new, evil identity for him.
** Another example is what happened to the Toa Mata. Due to their malfunctioning canisters, they drifted for such a long time in the ocean that their muscles rotted away ([[FridgeLogic even though the canisters were sealed]]) and their body parts got jumbled together. When they awoke and [[PullingThemselvesTogether put themselves back together]], it took some time for their lost identities to reemerge, however only their leader Tahu got his full memories back eventually.

[[folder:Video Games]]
* In ''Videogame/{{Earthbound}}'', when you initially get control of Poo he has an encounter where a spiritual being strips away his body and identity, and even though it's framed as a battle, you can't keep going unless you don't resist.
* This was a major plot revelation in ''Videogame/FinalFantasyVII'', when we discover that [[spoiler:Cloud Strife, due to psychological trauma and denial, had altered his own memories and adopted the persona of his dead friend Zack Fair, losing his own identity in the process.]]
* A main theme in ''Videogame/KingdomHeartsChainOfMemories'', where [[spoiler:Kairi's nobody,]] Naminé, was used by Organization XIII to rearrange and implant new memories into Sora's heart to make him a controllable pawn. Also happens to [[spoiler:Sora's nobody,]] Roxas, who's memories are wiped by Ansem the Wise and placed in a simulated world with a completely new identity.
** [[spoiler:Xion counts too. Her memories are just a copy of Sora's.]]
** [[spoiler:As well as Xehanort (or Terra's body with Xehanort's soul), whose memory was erased after being beaten by Terra's possessed armor and transported into Radiant Garden in Birth By Sleep.]]
** ...and the villains, who appear not to remember Sora and his gang despite him kicking their asses in the earlier games.
* This trope is the ultimate fear of [[VideoGame/SuperRobotWarsAdvance Lamia Loveless]]. When she asked the question "What is left from a soldier, when you take away their mission?", which got rebuked with the answer: "There's still human left!", she slowly starts noticing her identity as a normal soul (despite being ArtificialHuman). Further interaction and she finally learns to value her own identity, but feared that she would one day turn into a mindless doll, which prompts Kyosuke to promise her that he'd destroy her the moment she ever turns that way... But then, comes the ODE and Duminuss, all who attempted to rob her identity of a new human being and try to turn her into a mindless doll, like the way she was created, and almost succeeded permanently if it wasn't for Axel's interference (and a bit of her willpower).
* In ''VideoGame/MetalGearSolid'', after the [[NinjaPirateZombieRobot Cyborg Ninja]] slices off Revolver Ocelot's hand, he has a FreakOut upon seeing Solid Snake: He starts to bang his head against the floor while exclaiming that he's losing himself. To fix it, he picks a fight with Solid Snake, egging him on to [[GetAHoldOfYourselfMan hit him]]. It works, because he ''has'' been on the receiving end of Solid Snake's punches before, as [[spoiler:Gray Fox]]. Muscle memory trumps brainwashing.
* ''VideoGame/PaperMarioTheThousandYearDoor'': [[spoiler:Mario gets his identity and body stolen in the middle of a boss-fight by a Duplight-Ghost called "Doopliss". It seems that this even rendered him unable of pronouncing the word "Mario", since Vivian can't understand his answer when she asks him for his name.]]
* Nero Chaos in {{Tsukihime}} long ago lost his human identity in favor of a collective. The collective is also losing its identify and turning into chaos. Currently, he simply intends to live long enough to figure out exactly what ''that'' is.
* In ''VisualNovel/PhoenixWrightAceAttorney - Justice for All'', this is part of [[spoiler:Ini/Mimi Miney's]] motivation to murder. [[spoiler:She was in a horrible car accident in which the real Ini, her younger sister, was killed. She gave them Ini's photo to reconstruct her face with because she was ashamed of being the nurse whose mistakes (she partially blames on [[AssholeVictim the victim]]) killed patients. Then in her breakdown, she despairs that she had to keep living as her sister for the rest of her life.]]
** Also done in ''VisualNovel/PhoenixWrightAceAttorneyDualDestinies'' where [[spoiler: the Phantom, an international spy and assassin who caused the HAT-1 incident and is the murderer of Clay and Metis, claims he cannot remember who he once was or what he used to look like due to taking on the disguises of other people for so long.]]
* ''Kohan: Immortal Sovereigns'' does this with its Ceyah faction, who have abandoned Kohan society in search of greater power and adopted new identities; some go so far as to change their appearance by altering their form or donning a mask.
** The sequel adds new wrinkles to this by adding the Fallen faction - Kohan who have gone so far over the line that even the Ceyah want nothing to do with them; Ceyah who join the Fallen often abandon their ''Ceyah'' identities and mutate even farther. The Fallen's leader Abbadon is an extreme example of this; not only has he mutated into a city-smashing monster, but he gains the power to ''force'' the Fallen transformation in others, Ceyah or otherwise.
* ''PlanescapeTorment'''s entire story is arguably about this trope. [[RuleOfFun Up until the point where the player took over]], The Nameless One lost his identity every time he died. Trying to recover just who it is you 'are' through the multitudes of former yous who have existed across time is a cornerstone of the entire game.
* {{Persona 2}} turned this into even more horror with the Joker's curse. Sure, kid! Call in and get any wish you want! ''[[SchmuckBait Any wish!]]'' What they don't tell you is that if you're too weak or overuse the power, Joker drains you of your dreams, hopes and wishes, turning you into a Shadow Self that gradually fades into oblivion as you lose your identity to Joker's crystal skull. Funny thing, you see: the power to change reality ''is'' being fueled by your identity as an expendable resource. By rejecting reality and coasting by with Joker's power, you're weakening your connection to reality and getting closer to fading into a Shadow Self.
* ''VideoGame/DigitalDevilSaga'' has this as a potential side effect of the Demon Virus. The hardiest and strongest [[WasOnceAMan once-human]] enemies are almost all consumed by their demonic identities.
* Present in ''VideoGame/ShinMegamiTenseiIV'' [[spoiler:as part of Mastema's curse upon Michael, Uriel and Raphael, fitting the three with masks blotting their identities and power they were unable to remove by themselves. Eventually, [[NiceJobBreakingItHero with the help of the Samurai]], Gabriel springs them and removes the masks.]]
* [[LegacyOfKain Raziel]] goes through a fair amount of this. Wraith!Raziel (who [[AmnesiacDissonance doesn't remember his mortal life]] at all, just his vampiric and wraithly existences) meets Sarafan!Raziel and learns that his mortal self is a [[ColdBloodedTorture Sadistic]], [[HolierThanThou self righteous]] KnightTemplar douchebag. Vampire!Raziel was still a KnightTemplar but working for Kain instead of the Sarafan. Wraith!Raziel is still a KnightTemplar at points, but he's the poster boy for UnwittingPawn and CharacterDevelopment has left him with higher moral standards than his human or even vampiric self. He even calls his [[IHatePastMe former human self]] out [[EvenEvilHasStandards for his sadism]], tells him "[[ThatManIsDead I renounce you]]" and then kills him(self?). [[YourHeadAsplode Ouch]].
--> '''Human Raziel:''' "You're a righteous fiend, aren't you?"
--> '''Wraith Raziel:''' "[[{{Irony}} Apparently I am...]]"
* In ''VideoGame/ResidentEvil2'', Birkin suffers from this after his G-Virus induced [[OneWingedAngel transmutation]].
* In the NeverwinterNights fan module Excrucio Eternum, the elf girl Songbird has literally no sense of self because she has been in a cage her entire life, and has been brainwashed to refer to herself as "it".
* In the ''Franchise/MassEffect'' universe this is one of the early signs of Reaper indoctrination. The ability of victims to think clearly and maintain a sense of self degrades and they eventually become little more than slaves of the Reapers, believing them to be gods and the only good thing in the universe. And then come the [[UnwillingRoboticisation Dragon's Teeth]].
* Big Daddies in ''Franchise/{{BioShock}}'' normally are mind-wiped, but [[AndIMustScream some unfortunately retained their minds]].
* The main theme of ''GeminiRue'' with the government ([[spoiler:and {{Yakuza}}]]) operating a special center where the criminals ([[spoiler:or just enemies of the Boryokudan]]) are mind-wiped and re-trained for a time before a final wipe and the creation of a new identity and plastic surgery. One of the protagonists, Delta-Six (AKA Charlie) is one such mind-wiped individual at Center 7, whose eventual fate is to be [[spoiler:turned into the second protagonist Azriel Odin, a Boryokudan assassin; but his conscience takes over, and he becomes a cop instead]]. At the end of the game, [[spoiler:Azriel is mind-wiped as well and left a blank slate; however, Echo-Five believes he is now free to be himself]].

[[folder:Visual Novels]]
* Shirou of ''VisualNovel/FateStayNight'' suffered this during the fire ten years ago, where he lost all of his memories and even sense of self. Shirou's entire personality is built on his guilt from surviving and his admiration of how happy Kiritsugu had been when he saved him. When Archer points out how empty his dream and personality are it nearly destroys Shirou.

[[folder:Web Comics]]
* In ''Webcomic/{{Misfile}}'', Ash is turned into a girl and history is rewritten to reflect that Ash had always been a girl. Even though Ash has a good (apparently better) life, he believes that he can't give in because if he does, it's tantamount to suicide for boy!Ash. Worse, if the misfile is exposed and covered up, he won't have a choice any more. Ash is constantly proving to himself that he's still the Ash he remembers instead of the Ash that the rest of the world remembers.
* In a recent storyline of ''Webcomic/TheWotch'' (which generally tends to gloss over this trope), Ivan wrestles with this after he is [[GenderBender transformed]] as DisproportionateRetribution for snooping and trespassing by Miranda West, and eventually comes out for the better by reasserting his goals.
* Depending on how you look at things, Ellen in ''Webcomic/ElGoonishShive'' is either Elliot's OppositeSexClone, or a magical curse given human form. She has all of Elliot's memories up to the point when she split off from him, and initially believes herself to ''be'' Elliot, then [[CloningBlues snaps]] and tries to become a [[HarmlessVillain villain]] ([[PokeThePoodle with the emphasis on "tries"]]), then becomes a DeathSeeker, and finally [[spoiler:develops her own identity as Elliot's "sister."]]
** This trope is the reason that Justin refuses to allow himself to be permanently transformed into a girl (he knows that a girl being attracted to guys would earn him less ridicule than being a guy attracted to guys). Even if it would make his life easier, he still identifies as a man.
* In ''Webcomic/{{Jack|DavidHopkins}}'', it's one of the major plot points. The titular anti-hero/villain is undergoing eternal punishment for his sins (which, as it later turns out, include [[spoiler:wiping out the entire human race]]) - but his last wish in life, which was also part of the punishment, was not to remember anything. A major motive in the comic is Jack gradually regaining his memories - and the source of many people wondering, is he still the same person when he remembers everything?
* In ''Webcomic/TwoKinds'', this happens to Trace twice: first when his mind is destroyed, and again when he loses his memories. It's theorized that his nice side is real because that's how he was before lost his mind for the first time.
* In ''Webcomic/{{Sinfest}}''
** Lil Evil foolishly washes himself with the waters of the Lethe [[http://www.sinfest.net/view.php?date=2011-09-24 and wants to know who he is.]]
** When he has, thanks to AmnesiacDissosance, forged a new life, [[http://www.sinfest.net/view.php?date=2013-03-14 it perplexes Seymour, who asks who he is.]]
** The orange devil girl coped for a long time without even realizing. [[http://sinfest.net/view.php?date=2014-02-17 however, when introducing herself to the fembot, she realized that she didn't know her own name.]]
* In ''Webcomic/{{Archipelago}}'', Anthony becomes Blitz (a name Credenza gives him when he can't remember his own) after his mind is completely shattered and his memories lost when Raven's possession attempt goes horribly wrong. His former colleagues come across him weeks later and point out how he'd changed entirely, more or less becoming another person.
* In ''Webcomic/FarOut'', [[http://kimiq.com/farout/en/2013/02/06/farout-page-23/ the central robot starts to realize what he wants to be, though he has no clue who he is, or was.]]

[[folder:Web Original]]
* Happens in many, many Transformation, Robot, or other such things pictures, stories, comics, and other such things. There's a very good chance that, if transformed into something else, a character will cease to be who they are. Occurs often in the work of Arania, and also in some of the stories of Amhein.
** http://arania.kamiki.net
** http://www.process-productions.com/forum/showthread.php?t=16763
* Also frequently the end result of [[FountainOfYouth Age Regression]] works; after the character is physically age-regressed, they may or may not retain their memories and personality; however even if they do not immediately fall back into childish behaviour patterns, such changes usually happen whether they are preferable or not. This often affects memories as well, such that the process of regression will cause them to forget that they are regressing; it's hard to fight against something that you don't even know is happening to you until it's too late....
* In ''ArcanaMagi'', this happens to Alysia. To the point that she believes her new identity IS her real identity, even though she still has some of her real original memories intact.
* A common fate of victims in TheSlenderManMythos.
* In ''Literature/{{Worm}}'', [[spoiler:Taylor]] suffers mental deterioration from [[spoiler:Panacea tampering with her brain]] that erodes her memories and her sense of self and eventually results in a complete loss of identity.

[[folder:Western Animation]]
* ''WesternAnimation/AdventureTime'' has the Ice King, who WasOnceAMan, and lost his memory and most of his personality as he lost his humanity to an ArtifactOfDoom. Its implied he might still be in there somewhere, but buried so deep not even he knows it anymore.
* Spoofed in the ''SpongeBobSquarePants'' episode "Missing Identity", where [=SpongeBob=] misplaces his name tag and treats it as SeriousBusiness.
* In the ''WesternAnimation/TeenTitans'' animated series, Fixit tries to "repair" Cyborg by taking away all that made him human and replacing it with fully mechanical parts and a mechanical brain. Cyborg is justifiably freaked out, because, without his humanity, he'd be just a emotionless machine with his memories. Eventually, it is Cyborg's humanity that causes Fixit to remember what ''he'' lost.
* ''WesternAnimation/XiaolinShowdown'' - One of the Shen Gong Wu, The Monkey Staff, turns the user into a being with a similar appearance, strength, agility and balance to a monkey. However, if used too long, the user will believe that he or she is an actual monkey, and his or her human memories will be erased until the staff is taken away.
* ''ComicStrip/{{Popeye}}'' has one short where Olive Oyl invites Popeye over for a good meal; Wimpy, ever the BigEater, disguises himself as Popeye to get the food himself. Despite the LatexPerfection of the disguise, he still manages to come off as an OddballDoppelganger, yet Olive is fooled, and Popeye himself suddenly laments the possibility that he is not himself.
* In DonHertzfeldt's far-future [[TheSimpsons Simpsons]] [[CouchGag/{{TheSimpsons}} couch gag]], the design of the characters and the show changes so radically that by the year 10,535 the Simpson family has been reduced to a disturbing collection of caricatured mutants that can only sputter broken catchphrases and hock merchandise

* The MindManipulation tropes page would count, since it's about messing with people's loyalties and turning them against their friends and families.

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