->When a strange alien symbiote turns Franchise/SpiderMan's suit black, his darkest demons come to light - changing Spider-Man inside as well as out.
-->-- ''Film/SpiderMan3'' DVD back cover

This is for when a character who is normally neutral, good, or at least on the overall side of good, temporarily switches sides and/or has a noticeable temporary drop in morality. May be caused by a character being NotHimself. The character will go back to being his or her old self by either the end of the episode or the next episode.

Compare FaceHeelTurn & HeelFaceTurn, when a character either turns evil or good permanently or for a few episodes or seasons.

Contrast with JumpingOffTheSlipperySlope and/or MoralEventHorizon, which are more permanent. See also CompressedVice for problems other than villainy (though they may be cause for it) that last an episode.

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!! Examples:

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[[folder:Anime and Manga]]
* In the Black Rose duelist arc of ''Anime/RevolutionaryGirlUtena'', some of the people Utena has to fight are her brainwashed friends.
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[[folder:Comics]]
* During the late nineties, Comicbook/IronMan went insane and became a villain, only to be replaced briefly by a younger version of himself from a different time. He also TookALevelInJerkass and acted like a villain in the Franchise/MarvelUniverse for about a year after ''Comicbook/CivilWar''.
** [[spoiler: The Civil War thing was solved by a HeroicSacrifice, that knocked his mind back to a 'him' made before the Civil War.]]
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[[folder:Film]]
* While he doesn't quite become a full-blown villain so to speak, Spider-Man shows a semi-evil side in ''Film/SpiderMan3'' when the symbiote he has on his suit results in a major increase in vengefulness and aggressiveness. He doesn't switch sides; he's fighting against the same enemies as he was immediately before; but his "influenced" side has him doing things he severely regrets and that the series portrays as very clearly wrong.
* IndianaJones temporarily becomes a [[ReligionOfEvil Thuggee cult member]] in ''Indiana Jones and the Temple of Doom'' and nearly sacrifices Short Round and Willie in the process, but he manages to snap out of Mola Ram's mind-warping in time.
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[[folder:Live Action TV]]
* The EMH on ''Series/StarTrekVoyager'' was reprogrammed to perform unethical-at-best medicine by the Equinox crew.
* ''Series/BuffyTheVampireSlayer'' briefly toys with the dark side a few times. At the opening of season two (induced by trauma) and in a brief arc in season three.
** Done again in the ''Series/{{Angel}}'' episode "Sanctuary" where Buffy is the villain because she wants to kill Faith out of revenge.
** Willow at the end of season 6 when she becomes Dark Willow and eventually tries to [[WoobieDestroyerOfWorlds destroy the world]]. She gets better.
* ''Series/{{Charmed}}''
** In many episodes one of the Halliwell sisters will go to the dark side for a day before switching back by the end of the episode. A particularly notable one early on has all three sisters turn evil by the end of the episode, only for Leo to save them.
** Also, the episode where Paige does a spell to conjure up a 'Mr. Right' for 24 hrs which inadvertently also produces a 'Mr. Wrong' who she allows to seduce her with his seductive naughtiness.
* Duncan Macleod on ''{{Series/Highlander}}'' when he has the Dark Quickening.
* Clark on ''Series/{{Smallville}}'' when affected by Red Kryptonite.
* The [[DoctorWho Time Lord Victorious]] from "The Waters of Mars." He comes to his senses ''very'' quickly, though.
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[[folder:Professional Wrestling]]
* Wrestling/ShawnMichaels was basically always a face after his comeback in 2002, but he turned evil for about a month to beat up HulkHogan. Literally the night after the match he was back to being a good guy.
* Wrestling/StoneColdSteveAustin was always an AntiHero VillainProtagonist, since he was a face who did heel stuff, but in the [=InVasion=] angle he temporarily joined the invading WCW side, which was by definition the "bad" side of the angle. As soon as the angle was over he was back to his old self again.
** Actually, he was a villain even before the inVasion, forming an alliance with [=Vince McMahon=] and TripleH. He just went along with the rest of WWE against WCW/ECW as part of an EnemyMine scenario, and (because he was WWE Champion), everyone in WWE assumed he'd stand with them.
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[[folder:Video Games]]
* In the iOS game ''VideoGame/{{Highborn}}'', in Chapter 2, [[spoiler:Enzo becomes part of the Decay side for a while after marrying Jessica]].
* A slight subversion in VideoGame/ArtOfFighting, in which [[{{Bifauxnen}} King]] and [[SNKBoss Takuma]] were originally cast as villains who worked for series antagonist, [[BaldOfEvil Mr.]] [[TheDragon Big.]] The former was forcibly conscripted after being beaten by Jack and his gang, while the latter was blackmailed, by Mr. Big, who had [[IHaveYourWife kidnapped Takuma's daughter, Yuri.]]
** Shortly after the conclusion of the first game's events, King cut ties with Big and befriended the Sakazakis, while also becoming [[TheProtagonist Ryo's]] {{Love Interest|s}}. And Takuma returned to his family, where he resumed his position as head of the Kyokuugen Dojo.
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[[folder:Webcomics]]
* ''Webcomic/EerieCuties'': Chloe underwent a period of villainy when she donned the [[AmplifierArtifact Doom Panties]] prematurely. This caused her crush on [[spoiler: Layla's fiance, Dio]], along with her feelings of inadequacy, to draw out her SuperpoweredEvilSide. Thankfully, [[HeartwarmingMoments she got better]] and is back to [[http://www.eeriecuties.com/strips-ec/been_there_all_night her lovable self.]]
** And promptly shipped off to a spin-off series. :(
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[[folder:Western Animation]]
* In ''WesternAnimation/EdEddNEddy'', Jimmy was an antagonist in the episode "If It Smells Like An Ed."
** Ed himself is this in "Little Ed Blue" and "The Day the Ed Stood Still".
* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' uses this every now and then, typically with mild examples.
** Spike the dragon is normally good, but his envy in [[Recap/MyLittlePonyFriendshipIsMagicS1E24OwlsWellThatEndsWell Owl's Well That Ends Well]], at the attention Owlowicious is getting, drives him to do some very morally objectionable things, such as planting a fake mouse corpse to try to make it look like Owlowicious killed the mouse. [[note]]When called out on this, he runs away from home, tries to hide in a cave that happens to belong to another dragon... a dragon who seems like he's about to kill or at least severely hurt Spike... but Spike ends up getting saved, [[CrowningMomentOfHeartwarming by Owlowicious. And then Twilight Sparkle reassures Spike he still has an important place in their social circle, prompting Spike to apologize for what he's done]]. By the end of the episode, Spike is pretty much one of the good guys again.[[/note]]
*** A more threatening temporary villainy occurs during [[Recap/MyLittlePonyFriendshipIsMagicS2E10SecretOfMyExcess Secret Of My Excess]], when his greedy dragon nature gets out of control. When [[spoiler:Rarity, not knowing he is the same Spike, talks about how generous Spike was]], he feels ashamed of what he has become and immediately reverts back to his old self.
** Twilight Sparkle has this in "[[Recap/MyLittlePonyFriendshipIsMagicS2E3LessonZero Lesson Zero]]", when Twilight is driven insane in her rush to find a friendship problem, to the point where she deviously creates one herself. Her AppleOfDiscord plan, however, [[GoneHorriblyRight goes horribly right]].
** Trixie goes from a JerkAss and arrogant but ''hardly'' evil stage performer to a rather sadistic villain who takes over Ponyville in ''[[Recap/MyLittlePonyFriendshipIsMagicS3E5MagicDuel Magic Duel]]'' thanks to the influence of the [[ArtifactOfDoom Alicorn Amulet]].
** Rarity becomes this in "[[Recap/MyLittlePonyFriendshipIsMagicS4E23InspirationManifestation Inspiration Manifestation]]" after learning a spell that allows her to alter anything [[ImaginationBasedSuperpower with her imagination]], wanting to make Equestria a more beautiful place. By which she means transforming everything into a golden, gem-encrusted, or otherwise impractically gaudy version of itself.
* ''WesternAnimation/ThePowerpuffGirls''
** Buttercup was an antagonist in "Moral Decay."
** Blossom's golf club-stealing incident in "A Very Special Blossom."
** The Mayor becomes one in "Hot Air Buffon" when he tries to fight crime without the girls by using a hot air balloon with a boxing glove, but he ends up injuring innocent people, so the girls have to stop him.
* In ''WesternAnimation/RoswellConspiracies'', this happens to Sh'lainn twice;
** Once when she suffers from an affliction called "the iron death", which causes a banshee to go insane and [[OneWingedAngel merge with all the machinery around her]] after staying away from nature for too long.
** In another episode she's nicked by a vampire, who uses her blood to turn them both into vampire/banshee hybrids [[spoiler: she resists when she's asked to drain Nick dry, giving The Alliance time to turn up, knock them out and reverse the process.]]
* ''WesternAnimation/SpongebobSquarepants''
** Barnacle Boy switching sides over not getting enough food and respect.
** Mrs. Puff has one in "Demolition Doofus" which gets her dangerously close to crossing the MoralEventHorizon.
** Just about almost every main character have their moments of temporary villainy. Patrick Star, Mr. Krabs, and Squidward Tentacles in particular.
* ''WesternAnimation/TheFairlyOddParents'': Jorgen Von Strangle in the episode "Action Packed!". While he's normally merely a JerkAss (albeit with a HiddenHeartOfGold), Timmy's wish that his life was an action movie turns Jorgen into an action movie villain, who kidnaps fairies and uses a machine to suck the magic energy out of them and transfer it to himself, making him even more powerful and gigantically muscle-bound. Luckily, he's returned to normal when the wish is unwished.
* WesternAnimation/{{Rocko|sModernLife}} in "Power Trip" after ignoring Mr. Smitty who told him, "Don't push the green button!"
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