-> ''"I don't drop character 'til I've done the DVD commentary."''
-->-- '''Kirk Lazarus''' (as Lincoln Osiris), ''Film/TropicThunder''

This is when a character who is an actor (not an actor in RealLife who plays a character) goes so deep into their role that they end up temporarily forgetting their original self. They usually start MethodActing, and before anyone knows it are so immersed in the role they're playing that they almost literally ''become'' that role, forgetting their old name, life, and setting aside their original personality. It's worth noting that while this is analogous to BecomingTheMask, the character who becomes this is not a criminal or TheMole, may not even ''like'' the role they have immersed themselves in, and has gone so deep into the role that they don't lament any LossOfIdentity or even remember having been a different person (much less compare that life to the present).

While in this state the character may act against their own interests or those of their allies and loved ones, though [[GetAHoldOfYourselfMan a good slap may fix them]], or pushing a BerserkButton their normal self would take issue with. If the character had a previous psychological disorder, this may result in temporary LossOfIdentity or even forming one or more [[SplitPersonality Split Personalities]]. In extreme cases it may take {{Deprogram}}ing to bring them back.

This trope can be considered a mundane, non-[[AppliedPhlebotinum Phlebotinum]] version of getting hit with LaserGuidedAmnesia and having FakeMemories implanted.

A SisterTrope to CannotTellFictionFromReality.

Compare with BecomingTheMask, where con men or TheMole who grow to like their assumed identity more than their original one, and also ThatManIsDead, in which the character emphatically rejects his old identity. Compare also EnforcedMethodActing, where this is imposed on an actor.

Contrast BrainwashedAndCrazy and SplitPersonalityTakeover.


[[folder: Anime and Manga]]
* In ''Anime/YuGiOhZEXAL'', Fuya Okudaira, a child actor, is pressured by his StageMom to not speak with other children and to focus on his role as D.D. [[PsychicPowers ESPer]] Robin. While Fuya wants to be friends with other kids, he doesn't want to disappoint his mother. Upon coming across a [[ArtifactOfDoom Numbers card]] (which amplifies the user's desires, usually to a sinister extent) that takes a form similar to his mother, he begins to believe that he really is D.D. [=ESPer=] Robin, and vows to protect his card, No. 83: Galaxy Queen, as he would his own mother.
* In ''Manga/MidoriDays'', Seiji and his {{Delinquent|s}} friends get called upon to play the roles in a movie of the underlings of a character played by Aikawa Shou, their favorite actor. During Shou's tearful death scene, the boys get too worked up, rise up and beat the crap out of the actors playing the guys who killed him. The director decides to ThrowItIn.
* In the anime film ''Anime/PerfectBlue'', Mima confuses scenes from the TV series in which she acts with reality, played for MindScrew.
* In ''Anime/DotHackSign'', a limited version happens of this. Tsukasa knows he's in a videogame even though he can't leave the game and feels everything within it as though he were actually there, but [[spoiler:he's forgotten that in real life he's actually a girl.]]

[[folder: Comedy]]
* Gary Gulman has a routine where he talks about roleplaying a [[TeacherStudentRomance teacher-student]] [[SextraCredit scenario]] with his girlfriend as foreplay. Gulman quickly gets too caught up in his teacher persona and becomes more interested in his girlfriend passing her fictional class than having sex with her.

[[folder: Comic Books]]
* ''Franchise/{{Batman}}''
** Back when ComicBook/TheJoker had his own comic series in the 1970s, one of the opponents he faced was an actor who had started to believe he actually was Franchise/SherlockHolmes.
** The post-Comicbook/ZeroHour version of the second Two-Face, Paul Sloane, was reimagined as an actor so involved in method acting that he ended up turning himself into one of Franchise/{{Batman}}'s [[ThematicRoguesGallery deformed, psychotic rogues]] while researching a part.
** One of the possible deaths of Batman in ''Comicbook/WhateverHappenedToTheCapedCrusader'' has him trying, and failing, to talk down an actor who got lost in the supervillain part he was hired to play.
* In recent interpretations, Franchise/SpiderMan enemy the Chameleon sometimes has trouble discarding his assumed identities without some mental issues.
* In a 1970s story, a combination of psychological conditioning and PTSD left Creator/MarvelComics super-spy the ComicBook/BlackWidow mentally "stuck" in her cover identity as mousy schoolteacher Nancy Rushman.
* This was part of Judge Doom's backstory in ''[[Film/WhoFramedRogerRabbit Roger Rabbit: The Resurrection of Doom]]'', explaining why nobody knew who he really was until after the events of the movie.
* The Creator/{{Vertigo|Comics}} reboot of ''Series/HumanTarget'' made this a key part of Christopher Chance's success. He was so good at impersonating his clients that he actually built himself into their personalities in order to fool whoever was trying to take a swing at them, and required extensive deprogramming once a job was complete.
* A combination of the Scarecrow's Fear Gas and the mind-altering System lead [[ComicBook/{{Azrael}} Jean-Paul Valley]] to believe that not only was he Franchise/{{Batman}}, but the one ''true'' Batman, going so far as to claim that he was nothing if he couldn't be Batman.
* In the ''ComicBook/{{Tintin}}'' story ''[[Recap/TintinTheSecretOfTheUnicorn The Secret of the Unicorn]]'', Captain Haddock gets so wrapped up in the tale of [[IdenticalGrandson his famous ancestor Sir Francis Haddock]] that he runs off some visitors at cutlass-point in the belief they're pirates, and demolishes his room while relating the battle with Red Rackham.
* One ''ComicBook/JudgeDredd'' story involved an actor playing [[BigBad Judge Death]] at a tourist trap who got a little ''too'' immersed in the role. He begins talking like Death even when off the clock, and eventually starts hallucinating the real Death appearing to him and encouraging him to murder people. He snaps and kills his manager, then tries to kill a group of people in a bar with an axe. Dredd is forced to shoot him to save them. [[CrossesTheLineTwice Hilariously]], his manager continues to praise his MethodActing, [[SkewedPriorities even while being strangled to death]].

[[folder: Film]]
* This concept is a metaphorical interpretation of ''Film/BlackSwan''. Nina, sweet and a perfect representation of the White Swan, tries so hard to become the Black Swan that she loses herself.
* The 1947 FilmNoir ''Film/ADoubleLife'' is all about this, where an actor (Creator/RonaldColman) playing ''Theatre/{{Othello}}'' on Broadway finds his life being taken over by the role and eventually [[spoiler:follows in the part's footsteps when he murders his mistress.]]
* Deconstructed and parodied in ''Film/TropicThunder'' by Robert Downey, Jr.'s character. During the DVD commentary, RDJ stays in in character as Kirk Lazarus ''as Sergeant Lincoln Osiris'' until the very line of the movie where Lazarus-as-Osiris claims not to break character until the DVD commentary. When Ben Stiller calls him on it, he finally breaks character... and continues the commentary as Kirk Lazarus, acclaimed Aussie actor. It's only when Lazarus has his own "Who am I?" moment in the film that Robert Downey Jr. emerges.
* According to the sequel comic, Judge Doom of ''Film/WhoFramedRogerRabbit'' was originally [[spoiler:a Toon actor named Baron Von Rotten, who often played villainous roles (a deleted scene of the movie claimed Doom was the one who shot Bambi's mom). A concussion during a shoot led him to think he really was a villain.]]
* In ''Film/BadEducation2004'' Juan is only pretending to be [[spoiler:his dead brother, Ignacio]]. But in the process, Juan gradually ends up in the exact same situation, such as getting involved with the same men and dressing up as a transvestite.
* In a similar effect like the one in ''Perfect Blue'', Nikki Grace from ''{{Film/Inland Empire}}'' confuses her acting with reality, at a point where is impossible, even for the spectator to tell which is which.
-->'''Nikki:'''Damn... It sounds like dialogue from our script!
-->'''Kingsley:''' Cut, cut it.
* ''Film/GalaxyQuest'': Due to the premise, this is a recurring joke for the whole cast. Just about everyone has a moment where they forget their real selves, Guy especially (who only had a one-time bit part on the show). Hell, by the end, even Alexander is in on it, and he always ''[[IAmNotSpock hated]]'' his role!
* ''Film/TheHouseThatDrippedBlood'': In "Method for Murder", [[spoiler:Richard, the failed actor that Alice uses to play Dominick, the strangler from her husband Charles' book, in order to [[{{Gaslighting}} drive him insane]], becomes so immersed in the role that he actually believes he is Dominick and murders the psychiatrist, Charles, and finally Alice]].

[[folder: Literature]]
* Creator/KurtVonnegut's "Who Am I This Time?", featuring an actor who entirely inhabits his roles, because he doesn't really have a personality outside of them. Later adapted to an excellent made-for-TV movie starring Christopher Walken and Susan Sarandon, and directed by Creator/JonathanDemme.
* In Creator/RobertAHeinlein's ''Literature/DoubleStar'', the main character is hired to impersonate a kidnapped politician. He becomes so immersed in being this man that [[spoiler:after the original is killed, he takes over and actually becomes him. By the end of the book, he's forgotten he was ever anyone else.]]
* In the Comicbook/XWingSeries, Gara Petothel is a DeepCoverAgent formerly from Imperial Intelligence who no longer has anyone to deprogram her between missions. During one infiltration she's profoundly impacted by the PowerOfTrust and hopes to [[BecomingTheMask Become the Mask]] and embrace the role of Lara Nostil, a [[FarmBoy Farm Girl]]-turned-AcePilot. But then she's contacted by the (dead) Nostil's (fake) brother with a message from the BigBad, complete with doctored family holograms in the background that insert Gara into Lara's life. [[SanitySlippage This is not good for her already fragile mental state]].
** It's implied that going to the EDGE of this, is key to Imperial training. However, being away from her handlers has likely hurt her ability to keep from going over the edge.
** [[spoiler: In the end, it's played with. She purposely becomes lost in the cover identity of 'Kirney Slane'...but only to reclaim something as a 'real her'. She's still aware of Lara, and Gara, but chooses to identify with neither. Lara was a cover identiy, Gara was a bad person. Kirney can be someone new.]]
* In ''Literature/TheBarsoomProject'', a young [=LARP=]er named Michelle is handed a working rifle by a saboteur and unwittingly kills an extra in the Fimbulwinter Game. Unable to face what she's done, she convinces herself she really ''is'' her character, "Eviane", who'd shot the man because he was a villain trying to impose EndlessWinter upon the world.
* The titular hero of ''Literature/TheBelgariad'' discusses this with Silk, the TrueCompanions' resident thief and con artist, who has been employing an exaggerated version of his ''actual identity'' as an Alorn prince as a cover.
--> '''Garion:''' “I’ve been meaning to ask you about something. Always before, you acted almost as if you were ashamed of your title. Here in Mallorea, though, you seem to want to wallow in it.”
--> '''Silk:''' “What a fascinating choice of words.”
--> '''Garion:''' “You know what I mean.”
--> '''Silk:''' “In the West, my title’s an inconvenience. It attracts too much attention, and it gets in the way. Things are different here in Mallorea. Here, nobody takes you seriously unless you’ve got a title. I’ve got one, so I use it. It opens certain doors for me and permits me to have dealings with people who wouldn’t have time for Ambar of Kotu or Radek of Boktor. Nothing’s really changed, though.”
--> '''Garion:''' “Then all of that posturing and pomposity—pardon the terms—are just for show?”
--> '''Silk:''' “Of course they are, Garion. You don’t think I’ve turned to a complete ass, do you?”
--> '''Garion:''' “Then Prince Kheldar is as much a fiction as Ambar and Radek, isn’t he?”
--> '''Silk:''' “Of course he is.”
--> '''Garion:''' “But where's the real Silk?”
--> '''Silk:''' “It's very hard to say, Garion. Sometimes I think I lost him years ago.”
* ''Literature/WhoGoesThere'': The Things.
--> Garry spoke in a low, bitter voice. "Connant was one of the finest men we had here—and five minutes ago I'd have sworn he was a man. Those damnable things are more than imitation." Garry shuddered and sat back in his bunk.
--> And thirty seconds later, Garry's blood shrank from the hot platinum wire.
* This trope runs rampant through ''Literature/TheDayOfTheLocust'' as part of the book's critique of Hollywood artifice; almost all of the performers in the book dive so deep into inhabiting fake personalities for audiences that their real personalities have all but vanished.
** Washed-up vaudeville clown Harry Greener has spent so long using his suffering to entertain audiences that he now seeks out opportunities to regale unwilling but interested bar patrons with tales of his ruined life, from his over-before-it-began entertainment career to his marriage to a serial adulteress who ran away with a magician and left him to bring up their daughter, Faye, alone. Protagonist Tod Hackett reflects on Harry's permanently in-character status early in the book:
--->When Harry had first begun his stage career, he had probably restricted his clowning to the boards, but now he clowned continuously. It was his sole method of defense. Most people, he had discovered, won’t go out of their way to punish a clown.
** Harry's daughter Faye has been trained to use exaggeration as part of her dramatic performances, and while her acting career will likely never take off, she uses the same fakery as a defence against the harsh reality that she has no talent, viewing everything she does - including prostituting herself to pay for her father's funeral - as just another role.
** Faye's quasi-boyfriend, cowboy Earle Shoop, and his friends Calvin and Hink can no longer separate the characters they play in their very occasional western roles from the people they are offscreen, and spend their idle hours loitering in front of a saddlery store as if they were posing on a dusty frontier town set.
* Creator/HarlanEllison's short story "All the Sounds of Fear" has a particularly grotesque and tragic take on this. [[spoiler:{{Shapeshifting}} is involved, perhaps not entirely voluntary.]]

[[folder: Live-Action TV]]
* In an episode of ''Series/BuffyTheVampireSlayer'' Drusilla uses her psychic talents to appear to Giles as his former lover Jenny Calendar in order to seduce some information from him. She gets so carried away in the role that she continues making out with him for some time after learning what she was after.
** For that matter, the actors themselves would do this on more than one occasion. Memorably, Creator/SarahMichelleGellar was so invested in her character's romance with Angel that when he turns evil and abuses her, in the scene where she runs home and cries she is so broken up they had to close the set for half an hour.
** A parallel situation occurred in the first season of Series/{{Angel}}, when Angel has to give back his day as a mortal man. Both Sarah Michelle Gellar and David Boreanaz were at a literal breaking point at the end of the episode. Boreanaz gently whispered "Sarah, Sarah" to her, because her tears were genuine.
** Over a decade after the show ended, Creator/JamesMarsters said in an interview that the worst filming day of his career was still the day they filmed the episode in which Spike tried to rape Buffy. According to him, he can't even watch scenes like that in shows and movies, so being required to act it out, as the perpetrator no less, lead to him sitting in a corner curled up into a ball of misery between takes.
** Another example, this time overlapping with BecomingTheMask, was when Faith switches bodies with Buffy and then impersonates her for several days. She becomes so enamored with Buffy's heroic lifestyle ([[TrueCompanions with loving family and friends looking up to her]]), that when she has the chance to skip town free and clear she instead comes back to save innocent hostages from a group of vampires [[IronicEcho "because]] [[BorrowedCatchphrase it's wrong"]]. When Buffy-in-Faith's-body shows up to confront her afterwards, all Faith's own self-loathing comes pouring out in their fight; she beats the crap out of her former body while screaming that she's dirt, trash, and evil. Buffy is able to switch their bodies back, but is so shaken by what she just witnessed that she doesn't pursue Faith when she immediately flees.
* This was parodied in an episode of ''Series/{{Community}}'', when Abed told the story of creating and then ''becoming'' a character for his walk-on role in ''Series/CougarTown''.
** Danny Pudi filmed a cameo on ''Series/CougarTown'' in reference to this scene. It's glorious.
** Abed made up a role for him to play in Cougartown named Chad, and as he made up Chad's backstory in his head, he realized that he had spent all of his life to that point dedicated to pop culture, and Chad had a significantly more fulfilling life than he did. When filming ended and he was forced out of character, he [[HeroicBSOD had a mental crash]], fell over and [[BringMyBrownPants shat himself]].
** Parodied in "Documentary Making: Redux", wherein Jeff is reluctantly cast as the Dean for a short commercial for Greendale and is forced to wear a bald cap over his natural hair. The shoot is only supposed to be for one day, but thanks in part to Jeff's own efforts to try and get out of it it ends up going for almost two weeks – all of which time Jeff is forced to wear his Dean's costume. Over this time Jeff gradually begins to take on several of the Dean's character traits and becomes convinced that he's actually a bald man who "only dreamed of having hair".
*** This could also be an ActorAllusion--Joel [=McHale=] is actually balding (see [[http://www.complex.com/style/2012/12/the-50-worst-celebrity-hair-styles/joel-mchale this]] photo), and either wears a toupee or has had a hair transplant, depending on who you ask.
* This is arguably the super-power of Echo, the protagonist of ''Series/{{Dollhouse}}''. Despite repeated memory wipes, she always retains the "imprints" of the other personalities she's assumed.
* Possibly Sophie Devereaux in ''Series/{{Leverage}}.'' She mentions before her sabbatical that she's created so many fake personas she's not really sure what's really her anymore and leaves to bury each of them. This extends so far that we're not sure what her real name is.
* This was the plot point in the ''Series/{{Monk}}'' episode "Mr. Monk and the Actor," when a [=TV=] movie was being made about Adrian Monk, starring renowned actor David Ruskin as him. Except, Ruskin has a history of falling too deeply into his roles (for example, once having to spend three months in a rehab clinic after playing an alcoholic in a TV movie, because he managed to have all the symptoms of alcoholism without drinking), and when he portrayed Monk... Afterward, in session with Dr. Kroger, Monk notes that Ruskin has decided to try something less depressing, then adds "[[HypocriticalHumor He's in England playing]] ''Theatre/{{Hamlet}}''."
* An odd example with Jeremy Brett as ''Series/SherlockHolmes;'' he became ill ''while'' obsessing over the character – realizing that he was manic depressive allowed him to start overcoming his obsession to the point where he could enjoy playing Holmes. He died eleven years after ''Series/SherlockHolmes'' first aired, and had quit the series entirely the year before his death.
* In ''Series/TheTwilightZone1959'' episode "A World of Difference", this is what everybody thinks happened to Gerry Raigan, an alcoholic actor who seems to have snapped and identified too closely with happy executive character Arthur Curtis. He, on the other hand, thinks that he [[SchrodingersButterfly actually is Curtis]], trapped in a nightmare world.
* On ''Series/WKRPInCincinnati'', a well-paying job requires Johnny Fever to play an obnoxious, boisterous host of a televised disco dance show, to the point he actually does begin to lose himself, and becomes frightened this vile character will become him. Twice as interesting for the fact that Johnny Caravella already plays a role as Doctor Johnny Fever – but it is a role he likes. His best friend Gordon Sims tried to lose himself in the role of Venus Flytrap, to escape from the memories of his time in Vietnam. They catch up with him anyway.
* In an episode of the 1970s British TV series ''Series/{{Colditz}}'', an officer in the World War 2 German prisoner of war camp simulates insanity so that he will be repatriated to Britain, the plan being that he will then reveal himself as sane and return to action. His simulation succeeds only too well – at the end of the episode, the prisoners in Colditz receive a letter from the officer's wife relating that he actually went insane and is now confined to a mental institution. The escape committee then decides that no other prisoner in Colditz is to attempt that ploy.
* ''Series/{{Misfits}}'' had a FemmeFatale character who turned out to be this; she was auditioning for a part when the storm happened, and her power made her become that character. Unfortunately for everyone involved, this also means she subconsciously exerts a degree of MindControl, compelling the men she gets involved with to fall into the roles of her recurring story: first as her secret lover, then her savior from her abusive ex-, finally becoming her abusive ex- for the next guy in the cycle to save her from.
* One episode of ''Series/PressGang'' concerned an actor who played the lead role in children's adventure serial ''[[ShowWithinAShow Colonel X]]'', who had been severely typecast and 'drinking rather too much' before getting into a car crash which killed his wife. Unable to handle it, he started going around in-character as the Colonel, aided by how the press erroneously reported him dead along with his wife. (This is a mashup of problems affecting famous ''Series/DoctorWho'' actors Tom Baker and Rodger Delgado (who played the Master), and the Colonel is played in the show by Michael Jayston, who played the [[EnemyWithout not-quite-Doctor]] the Valeyard. The episode was written by Creator/StevenMoffat, who later went on to... well, yeah.)

[[folder: Newspaper Comics]]
* This was also parodied in a 2009 ''ComicStrip/{{Garfield}}'' strip, with the dialogue as follows;
-->'''General on TV''': Holy '''bovines''', Corporal! There's a giant monster invading the city!
-->'''Soldier on TV''': That's not a monster, sir.
-->'''General''': What are you talking about? Call out the artillery!
-->'''Soldier''': It's just [[PeopleInRubberSuits a bad actor in a rubber suit]].
-->'''General''': Oh, it is '''not'''! It's a monster!
-->'''Soldier''': Come on... I can see the zipper.
-->'''General''': Egad! A '''zipper''' monster! That's the worst kind!
-->'''Soldier''': And that's not a real city.
-->'''General''': '''Insolence!''' I'll have you '''court-martialed!!'''
-->'''Soldier''': These are just tiny little model buildings.
-->'''Garfield''': General Cordwood seems to have buried himself in the part.
-->'''Soldier''': See?
-->'''General''': PUT MY HOUSE DOWN!!

[[folder: Professional Wrestling]]
* Back in the days of {{kayfabe}}, it was normal for a wrestler to live his gimmick 24/7.
* During his run as the leader of the Wrestling/MinistryOfDarkness, it was hinted a few times that Wrestling/TheUndertaker was letting his character completely take over who he really was as a person. In a way, this was strengthening {{Kayfabe}} by breaking it.
* According to kayfabe, [[Wrestling/{{Boogeyman}} the Boogeyman]] was an aspiring television actor who couldn't let go of his commitment to a role after his horror series was cancelled.
** There were a lot of rumors floating around about him while he was wrestling; dirt sheets commonly reported that he actually did eat worms back stage (he'd eat them in the ring as part of promos to freak his enemies out...or just because) and that he'd stay in character all the time.
* Wrestling/ElSanto. Lucha Libre legend throughout the 50s and until his death in 1984. He became known for his silver mask, which he only removed once for the public eye, and was buried with it on.
* Wrestling/ReyMysterioJr, too, who in a sense ''is'' his mask. In fact, if you saw him bare-faced, you might not even know who it is.
* The guys behind ''Website/{{WrestleCrap}}'' have suggested this is what happened to Jim Hellwig, [[Wrestling/UltimateWarrior the Ultimate Warrior]], who went so far as to have his name legally changed to "Warrior."
** Born Joanie Laurer, Wrestling/{{Chyna}} did the same thing.
*** In both cases, it was merely a way to get around the WWE (with whom both had burned bridges) having copyright over the name by which they were known.

[[folder: Radio]]
* When the cast of ''Radio/ImSorryIllReadThatAgain'' reformed for their last series in 1973, after a five-year break, this phenomena was Lampshaded in a mainly-comic sketch. [[Series/TheGoodies Tim Brooke-Taylor]] was viewed as so identified with his famous radio personality of Lady Constance de Coverlet, that he simply ''couldn't'' get out of character. Fellow cast member [[Series/TheGoodies Graeme Garden]] - playing on the fact he genuinely is a qualified medical doctor - diagnosed the condition and performed an "operation" on set to surgically separate Tim from Lady Constance - incidentally parodying TV medical dramas and soap operas.

[[folder: Theatre]]
* ''Theatre/{{Hamlet}}'' is sometimes interpreted this way, with Hamlet's feigned insanity leading to him actually losing his grip on reality.

[[folder: Video Games]]
* ''VideoGame/MetalGear'' series:
** [[DeconstructorFleet As with so many other tropes]], this one is {{deconstructed|Trope}} in ''VideoGame/MetalGearSolid'': Decoy Octopus is so committed to his disguises that he requires ''deprogramming'' to leave his assumed identities after a mission.
** The purpose of the S3 program imposed upon Raiden in ''VideoGame/MetalGearSolid2SonsOfLiberty'' was to inflict this upon him, turning him from a former child soldier who rewrote his whole past with the power of denial into a second embodiment of Solid Snake.
--->'''Colonel''': This is a type of '[[{{RPG}} role-playing game]]'. The point is that you play out your part – and I expect you to turn in a perfect performance!
** In ''VideoGame/MetalGearAcid'', La Clown is able to 'become' Teliko so thoroughly that La Clown is able to access Teliko's memories and feelings, only breaking character when telling Snake her codename of Swallowtail. Apparently only a powerful psychic can detect the difference between La Clown's stolen memories and a person's real memories.
* In ''VisualNovel/PhoenixWrightAceAttorneyDualDestinies'', the BigBad is the phantom, an international spy who's spent so much time impersonating people that he's completely forgotten his original identity.
* In one of the many endings on the PC video game adaptation of ''Literature/AndThenThereWereNone'', one of the culprits is an actress who got too far into character and committed a murder for real.
* Martin Brown, one of the player characters of ''VideoGame/HotlineMiami2WrongNumber'', is an actor portraying Jacket in the fictional ''Midnight Animal'' film. In the dream sequence of one of his chapters, he professes his love of killing teenagers and attacks an interviewer. When confronted with [[TheGrimReaper Richard]], Martin tries to explain that [[MeanCharacterNiceActor it's only a film]], but Richard isn't buying it.
* In the ''VideoGame/BioshockInfinite'' DLC "Burial At Sea", it turns out that [[spoiler: the Booker you've been playing as is actually an alternate version of [[BigBad Comstock]]. In his universe, he accidentally caused the death of his Elizabeth and was [[MyGodWhatHaveIDone overwhelmed with horror and regret over what he did]]. In a desperate attempt to atone or at least calm his guilt, he found a universe that had no Elizabeth (that of [[VideoGame/Bioshock1 the original Bioshock]]) and took up Booker's name as a private detective who helped people in Rapture. At some point his deception became so thorough that he ''genuinely'' thought he was Booker, seeing no distinction between his real history and the cover story he made up for himself.]]

[[folder: Web Comics]]
* Taken to frightening extremes in ''WebComic/GuildedAge:'' The five main characters are online gamers selected to take part in a deep-immersion virtual reality role-playing game, and due to the unique magic/technology hybrid nature of the game, they think they actually ''are'' their game characters, with absolutely no memory of who they really are or the lives that they used to have.

[[folder: Web Original]]
* In ''Recap/TheFiveishDoctorsReboot'', several of the ex-Doctors are portrayed in this way as part of their copious AdamWesting. Creator/PeterDavison, for instance, is well aware that he isn't actually the Doctor but seems to think that he can actually use the TARDIS to travel in time, and Creator/TomBaker is portrayed [[AlternativeCharacterInterpretation ambiguously]] (via a FakeShemp) – he's either convinced he is the Doctor for real, or he ''actually is'' the Doctor for real.
* The [[http://shifti.org/wiki/Xanadu_(setting) Xanadu Storyverse]] has an inversion occur sometimes. Technically, it's BecomingTheCostume, but this only happens sometimes to someone who was changed. On the other hand, the costuming was a mass event. Changed people who have had their minds replaced are called "strangers".

[[folder: Western Animation]]
* In an episode of ''WesternAnimation/KimPossible'' [[AdamWesting The Fearless Ferret]] and White Stripe's actors forget they are actors and think they are their own characters.
-->'''Timothy North''': So what have you been up to lately?\\
'''Rudolph Farnsworth''': Oh living each day in delusion thinking fiction is reality. That's me.\\
'''Timothy North''': Me too.
* In an episode of the "Super Chicken" segment of ''WesternAnimation/GeorgeOfTheJungle'', an actor portraying a Snidely Whiplash-like character abducted the actress portraying the damsel in distress, making her a real DamselInDistress.
* In the second episode of ''WesternAnimation/UltimateSpiderMan'', Agent Coulson is made the new principal at Peter Parker's school, so he can keep an eye on Pete and his friends. Midway through the next episode, he calls Nick Fury, frantically begging for the full power of SHIELD... to help balance the school's budget.
* Happens in ''WesternAnimation/AFlintstonesChristmasCarol'', while Fred is busy rehearsing his part of Scrooge and starts acting like a selfish jerk to his family and friends.
* ''WesternAnimation/TheSimpsons'' has Duffman, whose actor--or at least one of them--openly admits he has no distinct personality out of his costume anymore and cringes to be called by his real name (Larry Duffman).
** It's later implied that this happens to all the actors playing Duffman, when Homer mentions he thought he heard he'd died.
---> '''Duffman''': Duffman can't die, [[TheOtherDarrin only the actors who play him]]. Oh yeah!
** One-shot minor Character Senor Ding-Dong was only a man playing the role of a doorbell company mascot, a Zorro-style hero who fixes doorbells with a whip. Then he just became that character entirely.
** Implied to have happened to the ventriloquist operating Gabbo, who repeatedly begs the ''puppet'' to stop calling the audience "SOB's", not realising that the camera was still rolling at the time.
* In ''WesternAnimation/SouthPark'', Cartman creates a very unfunny and very racist handpuppet impersonation of Jennifer Lopez for a diversity event. He soon completely loses control over everything he makes Jennifer do, and "she" gets a record deal despite Cartman's protests, engages in a sexual relationship with Ben Affleck, ends up in hospital thanks to assault from the real Jennifer Lopez, eventually reveals she is actually a con artist named Mitch Connor, swallows a CyanidePill and dies. Subverted in the final seconds of the episode when it's revealed Cartman was just doing it to convince Kyle that this trope was in play, so he could laugh at him about it.
** Although Mitch Conner returns in 200 and knows Mr. Hat, making this more confusing.
** "Super Fun Time" has the boys and their class visit a 19th century living history museum. There is a rule stating that the employees are not allowed to break character for any reason until the moment the work day ends, and the employees treat this rule as SeriousBusiness. A group of robbers who held up a Burger King takes everyone in the museum hostage and demand they give up the code to an electronically locked door so they can escape the police, and since electronic locks don't exist in the 19th century, the employees can't tell them, no matter how much they want to. When the robbers start killing employees for not cooperating, one employee decides to break character and tell them the code to make the killing stop. Before he can do so, one of the other employees ''takes the robber's gun and shoots him dead''. The kids ''and'' the robbers are absolutely dumbfounded.
--->'''Robber:''' You people are fucking insane!
* In an episode of ''WesternAnimation/DuckTales1987'' when an amnesiac Scrooge goes missing, the boys have Fenton impersonate him until he can be found. Fenton gets too caught up into the role and starts pinching pennies even harder than the real Scrooge, up to and including cutting both the housekeeper's pay and the nephews' allowances! When the real Scrooge finally regains his memory and starts proving himself to be the real deal, by this point Fenton has lost himself in the role so much that he tries to have his own boss arrested.
* In ''WesternAnimation/EdEddNEddy'', Double D and Eddy dress up Ed in a monster costume vaguely resembling a xenomorph in hopes that maybe he'd attract customers to their fair, but Ed's overactive imagination soon takes over and he soon starts truly believing he is a monster and starts attacking all the kids in the cul-de-sac.
---> '''Edd''': This is worse than I thought! This isn't as simple as pretending or play-acting, Eddy! Ed ''actually believes'' he's become a monster!
* ''WesternAnimation/TheLegendOfKorra'': Bolin does this when he gets some AcquiredSituationalNarcissism after playing Nuktuk, hero of the south, refusing to answer to his actual name, and not understanding why exactly the actress he works with isn't interested in him off-stage.
* Toph from ''WesternAnimation/AvatarTheLastAirbender'' seems to joke about this when she was playing the ''villain'' for training. When she throws a flaming boulder too close to Sokka she cries out:
-->'''Toph''': [[https://www.youtube.com/watch?v=v4YnyVdMjG4 I am not Toph! I AM MELON LORD!!!! MUHAHAHAHA!]]
* In an episode of ''WesternAnimation/PeterPanAndThePirates'' when Peter obtains Hook's hat he starts acting like a pirate captain himself. He gets so caught up playing the role though that he winds up literally believing himself to be a real pirate, to the point of even talking in Hook's voice. This ends up with the real Hook joining forces with him and Peter trying to feed Wendy to the crocodile!

[[folder: Real Life]]
* This is not unprecedented for practitioners of MethodActing, and can have very real and very negative effects on the actor in question. A good portion of acting training is in fact learning how to avoid this.
* After portraying Idi Amin (a brutal and genocidal Ugandan dictator) in Film/TheLastKingOfScotland, Forrest Whitaker had to go into a period of intense therapy to shake off the character.
* The Canadian actor Raymond Massey, best known for his many, many portrayals of UsefulNotes/AbrahamLincoln on stage, film, and television, eventually became so obsessed with perfecting his performance that he started to assume the vocal and physical mannerisms of Lincoln in day-to-day life, even appearing at social gatherings dressed in Lincoln-esque clothing. A friend said of his obsession, "Massey won't be satisfied until someone assassinates him."
* Rumours abounded that Creator/HeathLedger's [[Film/TheDarkKnight take]] on ComicBook/TheJoker was at least in part responsible for his death. The Joker's psyche certainly is unsettling, to say the least. His co-stars seem to debunk this theory as they said he seemed really relaxed between takes and on stage, and in no way exhibited behavior that supports this theory. Likewise, at the time of Ledger's death, he was working on another film, Creator/TerryGilliam's ''Film/TheImaginariumOfDoctorParnassus'' which was a comic performance and far less stressful.
* Andy Griffith noted that he had this problem when playing Lonesome Rhodes in ''Film/AFaceInTheCrowd'', and it led him to mostly stay away from such roles for the rest of his career.
* Combined with the substance abuse issues he had at the time, Music/DavidBowie was noted to at least be worried about this happening with some of his stage personas, particularly the unsettling and unpleasant Thin White Duke from Music/StationToStation, which in turn derived from his appearance in Film/TheManWhoFellToEarth. This led to him moving away from adopting full characters on stage at around the same time as he pulled himself out of his addiction. Later in life, Bowie said he was afraid that his Ziggy Stardust character would come back into his mind and drive him completely insane.
* The same thing nearly happened to Music/AliceCooper as his alcoholism spiraled out of control in the 1970s. A stay in a sanitarium pulled him out of it.
* Creator/PeterSellers. Directors often described him as [[FunnyCharacterBoringActor "not having any real personality of his own"]]. At one point during an interview, after demonstrating a wide variety of voices and character types, the interviewer asked if he was now speaking in his real voice. After some hesitation, he replied with a confused "I don't know." When Sellers was the guest on ''Series/TheMuppetShow'', unlike any other guest on the series, he never appeared on-screen out of character. During the "five minutes to showtime" intro, he's Inspector Clouseau from ''Franchise/ThePinkPanther''. This appearance is the source of his famous quote, "There is no me. I do not exist."
* Actors who played the Doctor from ''Series/DoctorWho'' have been prone to this, as the Doctor is said to be one of [[BrownNote those]] characters (much like SherlockHolmes) who just gets into an actor's head and erodes their identity, and prolonged exposure is extremely dangerous – most Doctors only play the character for short runs as a protective measure against this. A couple, however, slipped into this:
** Due to the serious mental health problems he was experiencing at the time combined with a punishing shooting schedule, Creator/WilliamHartnell, who played the first Doctor, is reported to have, at times, not known if he was the Doctor or not. He slipped into character to talk his way out of a parking ticket at one point, which is understandable, but apparently would also slip into character to get away from familial obligations, and occasionally even for no obvious reason.
** The other Doctor whose mental health tanked as a result of the role, Creator/TomBaker, would reportedly keep up character whenever he was out and about [[ContractualPurity for the benefit of child fans]], but seven years of being the Doctor both onscreen and off took its toll on both his stress levels and his ability to distinguish ''Doctor Who'' from reality. He was unable to stop comparing himself to the character and experienced intense self-loathing for not being so wonderful and heroic as him, in particular struggling to accept his inability to save people from real problems the way the Doctor could save people from monsters, and found himself succumbing to various personality flaws that he had but the Doctor was [[IncorruptiblePurePureness too perfect for]].
%% *** Of course, odds are that Baker wasn't all there to begin with. Nine years before he landed the role of The Doctor, he [[ParentalAbandonment abandoned his wife and kids]] to start his career in acting and sealed the deal by [[NiceCharacterMeanActor attacking his mother-in-law with gardening equipment]].
* Creator/BobHoskins had a tendency to hallucinate towards invisible animated characters for a short while after filming of ''Film/WhoFramedRogerRabbit'' wrapped up.
* Creator/DanielDayLewis dropped out of doing theatre when he appeared in a production of ''Theatre/{{Hamlet}}'' and had a breakdown in the scene where he confronted his father's ghost. He later admitted that he projected his own estranged father, the poet Cecil Day-Lewis, into his performance and actually believed he had seen ''his'' father's ghost.
* This can be a problem with less mature cosplayers at {{Fan Convention}}s and the like; one may become so absorbed in acting out the character they're dressed as that they go to harmful lengths to imitate the character, such as stalking and harassing cosplayers dressed as the character's love interests, often without those cosplayers' consent. It gets worse if the character is AxCrazy or [[{{Yandere}} unhealthily obsessed with said love interests]].
* Creator/MelBlanc, of ''WesternAnimation/LooneyTunes'' fame, once spent two weeks in a coma after a car crash. The best efforts of his wife, son, and doctors couldn't revive him- until a neurologist addressed him as WesternAnimation/BugsBunny ''and he responded in Bugs Bunny's voice!'' He likewise responded to the names of other characters he voiced; apparently, they had ingrained themselves even deeper in his mind than his real self.
* While making ''Film/ManOnTheMoon'', Creator/JimCarrey basically disappeared for a year and Creator/AndyKaufman took his place. When it was over, ''Carrey didn't even remember most of what he did in the movie'' and was so exhausted that he has to decline appearing as Andy in Music/{{REM}}'s tie-in video for "The Great Beyond."