History Main / AmnesiaDanger

* ''Film/MenInBlackII'', where MIB needs the memory-wiped Kay to come out of retirement to deal with the crisis at hand. And when he remembers being in MIB, it turns out he wiped his memory of the critical event, so they're still in trouble.

* In the film ''Film/{{Mirage}}'', the main character is unaware he has amnesia at all. His mind, to cover the amnesia, has filled in the blanks. This becomes a problem when hired killers pursue him, also unaware he has amnesia and can't give him the information they want.

For this trope to work; the character or object at hand must be completely oblivious to his/her capability to solve the current-tense conflict, or be so about the knowledge how to; followed with the ''base fact'' that said character once had the knowledge / ability to solve the issue.

* Zigzagged in ''WesternAnimation/AvatarTheLastAirbender'' fanfic ''FanFic/{{Foxfire}}''. Since Li's amnesia made him less angry and more friendlier, he has more friends and allies. On the other hand, Li nearly suffocates to death when Katara encases his head in ice blocking his airways. Katara did it to buy herself time, knowing that Zuko would melt it. However Li couldn't. More subtly, lacking Zuko's memories and experiences through trauma makes Li much more vulnerable emotionally as he's re-experiencing past trauma and living through new trauma for the first time without any of his coping mechanisms.

* It also happened in the sequel to ''Anime/CuteyHoney'', another Creator/GoNagai creation. In the first episode of New Cutey Honey, she spends a long while running from the {{Mook}}s of the [[spoiler:apparent]] BigBad until she gets her memories back and remembers she can kick their sorry butts easily.

* In a ComicBook/BlackPanther Arc Photon, once leader of ComicBook/TheAvengers, had kind of forgotten who she was and how to use her powers. This was unfortunate as the city she was in was having a [[ZombieApocalypse vampire apocalypse]], a situation her light based powers were ideal for dealing with. What's worse is that most of the other heroes don't really know her or what she's capable of and therefore aren't trying to get her to remember.
** Matter of fact, by the end of the story she still doesn't have her memories back (despite being a little better with her powers). [[ContinuityOverlap Somewhere]] down the line she eventually does lose her amnesia [[ComicBook/{{Nextwave}} though]].

* In one issue of the Franchise/{{Batman}} comics, Bruce forgot that he was Batman. ComicBook/{{Nightwing}} and Robin had to team up to protect him and get him to remember.
* ComicBook/DisneyDucksComicUniverse: In the Creator/DonRosa comic "Forget It!", Magica de Spell puts a curse on Scrooge and Donald Duck, which has the following effect: whenever they hear their names spoken in conjunction with another thing, they immediately forget the thing in question ever existed. Thus, they can't even open a door, because she makes them forget what doors are. And this is just the beginning...

[[folder:Fanfiction]]

* Played with in ''Series/{{Dollhouse}}'' episode 4, "Gray Hour". The whole theme of the series revolves around certain characters who are given amnesia and new personalities almost twice an episode. Then halfway through this episode, [[spoiler:one of these Actives loses her imprint as a master thief in the middle of a mission thanks to a remote wipe by the Big Bad.]] From there this trope is played straight. Interestingly, the Dollhouse's solution to the crisis is pretty ingenious. They give the same personality to a different Active and have her guide Echo by phone.

* Played with in ''Series/{{Dollhouse}}'' episode 4, "Gray Hour". The whole theme of the series revolves around certain characters which are given amnesia and new personalities almost twice an episode. Then halfway through this episode, [[spoiler:one of these Actives loses her memory in the middle of a mission thanks to a remote wipe by the Big Bad.]] From there this trope is played straight.
** Interestingly, the Dollhouse's solution to the crisis is pretty ingenious. They give the same personality to a different Active and have her guide Echo by phone.

** In "[[Recap/AngelS04E06SpinTheBottle Spin the Bottle]]", the heroes regress back to their teenage selves. Most of them had little or no fighting experience, and so the team find themselves unusually vulnerable - in addition to [[EntertaininglyWrong wrongly figuring out what was going on]].

* Happened to Lelouch in Episode 1 of ''Anime/CodeGeass R2''. He could have dealt with Britannia's attack with the help of La Resistance if he hadn't had his memories wiped, but instead of kicking Britannia's ass he spent the latter half of the episode running around. Uselessly.
** He more than makes up for it when he gets his memories back by [[spoiler:[[ItsGoingDown toppling a TOWER on top of his enemies]] while [[MagnificentBastard still managing to convince them that the amnesia hadn't been fixed.]]]]

* ''LightNovel/ACertainMagicalIndex'' has an example where a character thinks this is the case, but it actually isn't. Terra of the Left notes that Touma isn't using the full potential of Imagine Breaker, and correctly deduces that he has amnesia. However, the little that is shown of Touma before the amnesia indicates that he still didn't fully understand his power.

* The ''Series/RedDwarf'' episode "Thanks For The Memories" used basically the same plot, leading to mutual, mostly-joking accusations of plagiarism. Only in that case the memory wipe was simply because [[LetUsNeverSpeakOfThisAgain what took place was so embarrassing they all wanted to forget it ever happened.]]

** In [[Recap/StarTrekTheNextGenerationS5E14Conundrum "Conundrum"]], the entire crew of the Enterprise have their memories erased by aliens, in order to trick them into attacking the aliens' enemies.

** In [[Recap/StarTrekTheNextGenerationS4E14Clues "Clues"]], the crew of the Enterprise discovers evidence that their memories and records have been tampered with and backtracks...[[AmnesiaLoop only to discover that one of the things they've forgotten is that they had]] ''[[AmnesiaLoop agreed]]'' [[AmnesiaLoop to having their minds wiped in the first place]] to appease powerful aliens who don't want anyone to know they exist. They convince the aliens to wipe their memories again, this time making sure to eliminate the things that served as clues the first time.
* In the ''[[Series/StarTrekTheOriginalSeries TOS]]'' episode [[Recap/StarTrekS3E3TheParadiseSyndrome "The Paradise Syndrome"]], the danger was that the amnesiac character (Kirk) had forgotten that there ''was'' a danger. Hilariously, the main thing he knew that (once remembered) saved the day was learned literally second before he lost his memory.

[[folder:Film — Animated]]

[[folder:Film — Live-Action]]

* Used in ''VisualNovel/PhoenixWrightAceAttorneyJusticeForAll'' as an excuse to give [[HeKnowsAboutTimedHits a tutorial]] to players that never played the original game. In truth, Phoenix has all but solved the case when he gets clonked on the head and loses his memory.
** ''VisualNovel/ApolloJusticeAceAttorney'' uses this for a backstory mystery. [[spoiler:Were it not for Lamiroir's memory loss, she could have simply told Apollo and Trucy herself that she was their mother and that they were half-siblings.]]
** In ''Dual Destinies'', [[spoiler:the trauma of walking in on her mother's murder caused Athena to completely block it out. While she didn't see enough to figure out who the actual culprit was, it did mean that she began to suspect that she ''did'' commit the crime, as several others argued. Her memories of the event were able to turn up necessary details to figure out who committed the crime and why.]]
* ''Franchise/{{Danganronpa}}'': Traditionally, all of the participants in the killing games are missing a good chunk of their memories and could have easily solved the plot if they could remember. [[spoiler: Justified, since the BigBad wiped their memories ''specifically'' so they'd be easier to manipulate]].
** ''VisualNovel/DanganronpaTriggerHappyHavoc'': Kyoko Kirigiri doesn't remember what her talent is, [[spoiler: because she's the Ultimate Detective, a major StoryBreakerPower for a murder mystery]], and all of the cast have forgotten that [[spoiler: they went to Hope's Peak together, were good friends, and had locked themselves in the school ''intentionally'' to ride out an apocalypse in the outside world. If they'd known these things, nobody would ever have killed anyone else]].
** In ''VisualNovel/Danganronpa2GoodbyeDespair'', this is [[spoiler: subverted, as the class regaining their memories is a ''bad thing''; the amnesia was a therapy technique to cure them of being BrainwashedAndCrazy, and when Mikan does remember, she turns from a NiceGirl to the third murderer.]]
** In ''VisualNovel/DanganronpaV3KillingHarmony'', the students start out missing memories and have some returned in stages later on by Flashback Lights. If they'd known everything from the beginning, [[spoiler: they'd have realized they were in a TrumanShowPlot, and all the "memories" the Flashback Lights gave them were fake.]]

* In ''Kagetsu Tohya'', the ''VisualNovel/{{Tsukihime}}'' sequel, Shiki has been made to forget about what his eyes can do [[spoiler:because if he can see death, he can see the world collapsing and Len will have to rewrite everything again]]. So he repeatedly comes upon circumstances that would be no big deal and then wonders why he thought he could deal with such a thing. Like being chained or locked out of a room. [[spoiler:Or knife fighting someone to the death.]]

->'''Leonard:''' ''[thinking while running]'' OK, so what am I doing?\\

'''Leonard Shelby:''' No... he's chasing me.

* The Stand Jail House Lock in ''Manga/JojosBizarreAdventureStoneOcean'' takes advantage of this to an extreme degree. The Stand attenuates the victim's short-term memory to the point that they cannot retain more than three facts at any time. If the villain for instance shoots four bullets at Jolyne, at the point she notices the fourth one ''she'll forget they fired the first one''.

** Matter of fact, by the end of the story she still doesn't have her memories back (despite being a little better with her powers). [[ContinuityOverlap Somewhere]] down the line she eventually does lose her amnesia [[ComicBook/NextWave though]].

* Used in an episode of ''Series/MyHero'' in which Thermoman, whose powers include erasing people's memories, inadvertently erases his own memory of being Thermoman. This, of course, coincides with the discovery of a giant meteor hurtling towards the Earth.

** [[spoiler:The [[LossOfIdentity memory-wiped]] Connor is fighting Sahjhan and losing decisively until Wesley inadvertently returned some of his memories mid-fight. About 6 seconds later Sahjhan was decapitated.]]
** In "[[Recap/AngelS04E06SpinTheBottle Spin the Bottle]]", the heroes regressed back to their teenaged selves. Most of them had little or no fighting experience, and so the team found themselves unusually vulnerable - in addition to wrongly figuring out what was going on.

* Played with in ''Series/{{Dollhouse}}'' episode 4, "Gray Hour". The whole theme of the series revolves around certain characters which are given amnesia and given new personalities almost twice an episode. Then halfway through this episode, [[spoiler: one of these actives loses her memory in the middle of a mission for real.]] From there this trope is played straight.

* ''Series/GameOfThrones'' - Things would have been a lot simpler if Bran could recall how and why he fell.

** In "[[Recap/StarTrekTheNextGenerationS5E14Conundrum Conundrum]]", the entire crew of the Enterprise have their memories erased by aliens, in order to trick them into attacking the aliens' enemies.

** In "[[Recap/StarTrekTheNextGenerationS4E14Clues Clues]]", the crew of the Enterprise discovers evidence that their memories and records have been tampered with and backtracks...[[AmnesiaLoop only to discover that one of the things they've forgotten is that they had]] ''[[AmnesiaLoop agreed]]'' [[AmnesiaLoop to having their minds wiped in the first place]].
* In the ''[[Series/StarTrekTheOriginalSeries TOS]]'' episode ''The Paradise Syndrome'', the danger was that the amnesiac character (Kirk) had forgotten that there ''was'' a danger. Hilariously, the main thing he knew that (once remembered) saved the day was learned literally second before he lost his memory.

* In ''Literature/{{Worm}}'', Bonesaw of the Slaughterhouse Nine creates a plague that inflicts prosopagnosia[[note]]inability to recognize faces[[/note]] on the people infected. Skitter, the protagonist, is attempting to find and kill the last surviving members of the Nine after she and the Protectorate have managed to eliminate or neutralize the others, before the plague hits and they all end up fighting one another. It's at that point that she runs into a handsome older white man and a prepubescent girl, whom she believes to be her teammates Grue and Tattletale. As the readers know but Skitter doesn't, the real Grue is black and both he and Tattletale are teenagers. The fake Grue is actually [[spoiler:Jack Slash]] and the fake Tattletale is [[spoiler:Bonesaw herself]].

* Stop and think for a second about how much less story there would have been in ''Manga/RaveMaster'' if Elie had never lost her memories.

* In ''Literature/{{Animorphs}}'' Megamorphs #1: The Andalite's Gift, Rachel endures [[TapOnTheHead head trauma]] and loses her memory. As a result, she spends most of the book lost in the woods since she can't remember who she is or that she can morph to help find her way out.

-->--'''from ''Film/{{Memento}}'''''

* In the ''Manga/DetectiveConan'' non-canon movie, ''Captured in Her Eyes'', Ran witnesses someone nearly killing a police officer friend of hers and, as a result, undergoes a severe case of TraumaInducedAmnesia. This puts her in danger in two ways, when the killer decides to off her because [[HeKnowsTooMuch she knows too much]]. The first is that while she saw the identity of the killer, her amnesia means she can't recognize him [[spoiler:even though she repeatedly sees him when he treats her as her doctor]]. The second is that she completely forgets her knowledge of fighting, so she's more or less defenseless when the killer makes several attempts on her life. [[spoiler:When she ''does'' get her memories back, she gives the killer an ''epic'' beatdown to make up for it.]]