History Main / AlternateIdentityAmnesia

This trope is about characters with a form of InvoluntaryShapeshifting or SuperPoweredEvilSide that causes them to suffer amnesia whenever they transform to their alternate form or self. Typically this trope is most often used in media with [[OurWerewolvesAreDifferent werewolves]] (or any other sort of [[OurWerebeastsAreDifferent werecreatures]]), though characters with a ''[[Literature/TheStrangeCaseOfDrJekyllAndMrHyde Jekyll And Hyde]]'' style SplitPersonality, DemonicPossession, or an EnemyWithin may also suffer from this form of amnesia. When it happens it may be immediately noticeable to the character; they will freak out at suffering blackouts and [[WhatDidIDoLastNight waking up naked in a field]], covered in blood, and surrounded by animal carcasses[[note]](hopefully it'll be ''just'' animal carcasses; human body parts are also a distinct possibility)[[/note]].

** In UsefulNotes/TheGoldenAgeOfComicBooks you had a standard JekyllAndHyde case. At first Thorn was an enemy of the Jay Garrick [[Franchise/TheFlash Flash]], and after being cured of Thorn, Rose became the wife of the original Franchise/GreenLantern. Too bad it couldn't last; Thorn resurfaced and Rose had to stop her for good with a HeroicSacrifice.
** UsefulNotes/TheBronzeAgeOfComicBooks[=/=]ComicBook/PostCrisis Rose and Thorn are another story. Thorn is a BadassNormal superhero initially out to [[YouKilledMyFather bring the gang that her/their police officer father died against]] to justice. DependingOnTheWriter, either each knows the other exists, but don't remember what the other did while in charge, so they have to write to each other, or Thorn "awakens" with knowledge of whatever injustice Rose has witnessed, but Rose is completely unaware of this.

** The UsefulNotes/BronzeAgeOfComicBooks[=/=]ComicBook/PostCrisis Rose and Thorn are another story. Thorn is a BadassNormal superhero initially out to [[YouKilledMyFather bring the gang that her/their police officer father died against]] to justice. DependingOnTheWriter, either each knows the other exists, but don't remember what the other did while in charge, so they have to write to each other, or Thorn "awakens" with knowledge of whatever injustice Rose has witnessed, but Rose is completely unaware of this.

* Rose and Thorn of Franchise/TheDCU. In UsefulNotes/TheGoldenAgeOfComicBooks you had a standard JekyllAndHyde case. At first Thorn was an enemy of the Jay Garrick [[Franchise/TheFlash Flash]], and after being cured of Thorn, Rose became the wife of the original Franchise/GreenLantern. Too bad it couldn't last; Thorn resurfaced and Rose had to stop her for good with a HeroicSacrifice. In the modern era, ComicBook/PostCrisis Rose and Thorn are another story. Thorn is a BadassNormal superhero initially out to [[YouKilledMyFather bring the gang that her/their police officer father died against]] to justice. DependingOnTheWriter, either each knows the other exists, but don't remember what the other did while in charge, so they have to write to each other, or Thorn "awakens" with knowledge of whatever injustice Rose has witnessed, but Rose is completely unaware of this.

* Rose and Thorn of Franchise/TheDCU. In UsefulNotes/TheGoldenAgeOfComicBooks you had a standard JekyllAndHyde case. At first Thorn was an enemy of the Jay Garrick [[Franchise/TheFlash Flash]], and after being cured of Thorn, Rose became the wife of the original Franchise/GreenLantern. Too bad it couldn't last; Thorn resurfaced and Rose had to stop her for good with a HeroicSacrifice. In the modern era, ComicBook/PostCrisis Rose and Thorn are another story. Thorn is a BadassNormal superhero initially out to [[YouKilledMyFather bring the gang that her/their police officer father died against]] to justice. Each knows the other exists, but don't remember what the other did while in charge, so they have to write to each other.

* ''VisualNovel/ExtraCaseMyGirlfriendsSecrets'': Sally has episodes where she doesn't remember what she was doing. [[spoiler:She is almost never conscious at the same time her SplitPersonality, "Seira"/Shadow, takes over her body, though she does sometimes have vague dreams about the latter's crimes.]]

* ''Literature/{{Seekers}}'' @ At first, Ujurak forgets he's a bear when he's in another form. He finally figures out how to keep his memory in ''Fire in the Sky''.

* Ujurak from ''Literature/SeekerBears'' forgets he's a bear when he's in another form.

[[folder:Film]]

* Zigzagged with the ComicBook/IncredibleHulk as there have been periods when Bruce Banner cannot remember anything about what happened when he was the Hulk (and vice versa) times when the memories are kind of fuzzy, and other times when one or both of them remember the other's actions clearly.
* ''ComicBook/IncredibleHulk'':
** She-Hulk experienced this twice: First, during the "The Cosmic Squish Principle" arc, when her savage Grey form first manifested. And later, during the ''Avengers'' arc "The Search for She-Hulk", as the exposure to fellow Avenger Jack of Hearts (who can manipulate radiation, although he isn't always able to do this consciously) caused Jennifer to lose control of her She-Hulk form. In both cases, she returned to normal a while after.
** This happened to Amadeus Cho whenever his Dark Hulk persona took control of their Hulk form.

** She-Hulk experienced this twice: First, during the "The Cosmic Squish Principle" arc, when her savage Grey form first manifested. And later, during the ''Avengers'' arc "The Search for She-Hulk", as the exposition to fellow Avenger Jack of Hearts (who can manipulate radoation, albeit is not always doing it consciously) caused Jennifer to lose control of her She-Hulk form. In both cases, she returned to normal a while after.

** This was also the case with Martin Li/Mr. Negative for a long time.

* ''Franchise/MarvelCinematicUniverse'': Zigzagged, as sometimes Bruce Banner cannot remember anything that happened while he was the Hulk (i.e. [[spoiler:the years spent on Sakaar]] before ''Film/ThorRagnarok''), and sometimes the memories are fuzzy or even clear (i.e. in ''Film/AvengersInfinityWar'' he explains to other Avengers what happened [[spoiler:to Thor and the Asgardians]] while he was "hulked out").

** ''Literature/HarryPotterAndTheChamberOfSecrets'': [[spoiler:Ginny Weasley]] finds she's having days where she wakes up in one room and has no idea how she got there, over and over. Gradually she starts to put it together that [[spoiler:the diary of Tom Riddle is possessing her in order to unleash the Basilisk.]]

** At the end of "[[{{Recap/BuffyTheVampireSlayerS1E6ThePack}} The Pack]]" where several students are possessed by hyenas, Xander says he doesn't remember what happened during that time. [[spoiler:Giles privately confronts him, saying none of the other students displayed amnesia, and Xander admits he just doesn't want to talk (or think) about it.]]

* [[spoiler:Red Riding Hood]] in ''Series/OnceUponATime'' suffers from this regarding her werewolf transformations and murders. However, she eventually learns to control her wolf self
* In ''Series/PowerRangersDinoThunder,'' initially Trent doesn't remember what he does when the White Ranger [[TransformationTrinket dino gem]] takes control. Eventually, he remembers, but can do little to stop it. This proves to be a bad thing - after a certain point, his dark side is in control ''all'' the time. [[spoiler:Eventually, the gem is drained of some of its energy, resulting in Trent being himself full-time, but at the cost of some of its power. For once, the way a SixthRanger is never quite as powerful after his early appearances is justified.]]

* In ''VideoGame/{{Elsword}}'', Ara's backstory has this. After she gained the mystical hairpin with a {{Kitsune}} spirit sealed within and almost get killed by her brainwashed brother, she gets unconscious. The next thing she knew after she "woke up" is that she had battled her brother and the demon army ''unconsciously'' - it's the fox spirit that did it for her.

* ''Series/TeenWolf'':

* ''Manga/AyakashiTriangle'': Matsuri [[AmnesiaEpisode spends some time]] hypnotized into believing he was always a girl, showing a completely different personality that lack any of his original memories. After changing back, he regards the things he did (including falling in love with Soga) as a "weird dream" that he doesn't dwell on.

* She-Hulk experienced this twice: First, during the "The Cosmic Squish Principle" arc, when her savage Grey form first manifested. And later, during the ''Avengers'' arc "The Search for She-Hulk", as the exposition to fellow Avenger Jack of Hearts (who can manipulate radoation, albeit is not always doing it consciously) caused Jennifer to lose control of her She-Hulk form. In both cases, she returned to normal a while after.
* This happened to Amadeus Cho whenever his Dark Hulk persona took control of their Hulk form.
* ''ComicBook/RobinSeries'': Stanley Baumgarten thinks he just has a sleep disorder when instead the mystical entity the Dark Rider has been possessing him at night and making money as a magic using assassin in Stan's body. He is horribly confused the first time he wakes up on the sidewalk in cuffs.
* ''Franchise/SpiderMan'': Norman Osborn is [[DependingOnTheWriter sometimes]] unaware of the Green Goblin's actions (most notably, the Goblin knew Spidey's {{secret identity}}, but Norman didn't).

* When [[ComicBook/CarolDanvers Ms. Marvel]] started out as a superhero, she would involuntarily black out and change to her alter ego. She wasn't initially aware that she was a superhero.

* In ''Film/MeMyselfAndIrene'', Charlie Bailygates can’t remember is behavior or words when his bad mood shifts into Hank.

* [[Anime/YuGiOhVRAINS Specter]] in ''Fanfic/InfinityTrainKnightOfTheOrangeLily'' doesn't remember anything when his SplitPersonality Easter takes control except a splitting headache caused by Paul London knocking Easter out with his staff. Even when Gladion, London and Tokio spell it out for him, he's in disbelief. By the time they reach the Windfish Car, he becomes horrified whenever he switches back.