'''DC'''
* Hal Jordan, ''ComicBook/GreenLantern'' poster child, underwent a psychotic turn into a being that wanted to reshape all of existence. Later [[AuthorsSavingThrow explained]] and {{Retconned}}, but still heavily controversial.
* ComicBook/TwoFace, in the Franchise/{{Batman}} comics is a good-guy district attorney who turns into an evil criminal.
* [[ComicBook/{{Batgirl 2000}} Cassandra Cain]] to a lot of disapproval. After spending 76 issues delving into her extraordinary psychology and fleshing her out into a complex character with high moral standards, DC tore her down and made her into a drugstore-variety DragonLady who started killing people like roaches. After an IMMENSE backlash, they very "cleverly" revealed that she was actually {{brainwashed}} by Comicbook/{{Deathstroke}} the entire time.
* In a particularly bad example of ExecutiveMeddling, DC planned to turn ComicBook/CaptainAtom into supervillain [[ComicBook/{{Armageddon 2001}} Monarch]]. When readers guessed the plan ahead of time, they changed their minds at the last minute and made the character [[ComicBook/HawkAndDove Hawk]] murder his partner Dove and don Monarch's armor. Then, in a series of decisions years down the line, they effectively reversed it, giving Hawk the new handle of Extant, putting Captain Atom into Monarch's armor and creating a new Hawk and Dove team.
* In ''[[ComicBook/{{Convergence}} Convergence #6]]'', [[spoiler:Superman and the rest of the heroes from ComicBook/KingdomCome. While the story they come from arguably ended the Dark Age of Comics and brought back idealistic heroes, These versions agree to serve the openly Tyrannical Deimos and fight the heroes of ComicBook/{{Earth 2}} if it means their own city surviving]]. This is turned back immediately after [[spoiler:Parallax murders Deimos]], as they had no reason to be evil anymore.
* Subevrted in ''ComicBook/DeathOfTheFamily''. [[spoiler: Harley Quinn is blackmailed into helping the Joker when he threatens to destroy Deadshot's corpse (Harley doesn't know that Deadshot is not dead though), after realizing Harley has feelings for Deadshot and is quite pissed off about it. If you did not read Suicide Squad, you would not know about it and think she had gone evil again.]]
* Mandrakk, the Dark Monitor from ''ComicBook/FinalCrisis'', was a Lovecraftian Horror ultra-vampire who wanted to feed on the life blood of existence itself until it had been bled dry. Saying he was the Ultimate Evil is not pushing the envelope. If what has been suggested - namely that he originally was the Monitor, the heroic mentor figure who laid down his life so the Universe might live in ''ComicBook/CrisisOnInfiniteEarths'' - is true, then this might be the ultimate FHT in comics.
* [[Franchise/GreenLantern The Guardians of the Universe]], having been SlowlySlippingIntoEvil ever since ''Rebirth'', finally crossed the MoralEventHorizon following the ComicBook/{{New 52}} -- they lobotomize Ganthet to get him back on their side, [[spoiler: seemingly kill Hal and Sinestro]], and begin a campaign of [[TheEvilsOfFreeWill removing free will]] from the universe by [[AssimilationPlot absorbing all life into their Third Army]].
* ''ComicBook/InfiniteCrisis'' did this to Alexander Luthor, Jr. and Superboy-Prime, two of the heroes from ''ComicBook/CrisisOnInfiniteEarths''. Alex turned due to jealousy towards Prime and Kal-L, the Golden Age Superman; both were able to have a childhood and future Alex did not. Alex later convinces Prime to help him with the idea that he could revive Earth-Prime and save his family. Prime ends up fully turning after he knocks Pantha's head off.
* [[ComicBook/{{Shazam}} Mary "Damn" Marvel]] provided an interesting contrast as a Golden Age teen amidst modern comics characters. Unfortunately DC decided to make her turn evil. Her clothes [[PaintItBlack even turned black]].
* The chief antagonist of ''ComicBook/TheMultiversity'' is a former "cosmic defender". [[spoiler:Nix Uotan]]. He [[RedemptionEarnsLife gets better]] in the last issue.
* Name a [[ComicBook/TeenTitans Teen Titan]]. Chances are good he/she has tried to kill the other Titans at some point. ComicBook/{{Raven}}, Jericho, and Beast Boy (yes, even BB) are some of the more well known ones.
** Raven and Jericho have frequently gone insane and/or evil to the point that it has practically become a RunningGag.
** Rose Wilson was drugged into becoming the Ravager by her father Deathstroke.
** Roy Harper became a psychotic anti-hero after he was mutilated and lost his daughter.
** Donna Troy was revived and brainwashed by the Titans of Myth after she was killed by the Superman robot.
** Cyborg nearly lost all his humanity when he became Cyberion and almost destroyed the moon.
** Osiris was forced to kill people in order to revive his sister, but by then he embraced a new love of killing and turned into a psychotic SpoiledBrat.
** Duela Dent's fractured mind means she's constantly switching from good, evil, and in-between. Her last appearance before she died had her attempt a kidnapping of a famous young actress.
** Risk turned against the Titans due to the resentment of being abandoned by them after losing his right arm. Although an early issue said Risk turned to petty crime after his Titans team disbanded.
** Power Boy turned out to be a StalkerWithACrush obsessed with Supergirl, and tried to kidnap and brainwash her.
** Golden Eagle tried to kill and replace Hawkman as revenge for his father's death.
** Deathwing, the supposed future version of Dick Grayson who belonged to the Team Titans, was brainwashed by Raven and raped Mirage. Even after the supposed brainwashing wore off, he remained a bad guy.
** Hank Hall, the first Hawk, went completely off the deep end when Dawn Granger died, becoming Monarch and later Extant. It turned out Hank had some help from Mordru the Merciless, but as a revived Dawn stated, Hank moved well beyond Mordru's control and turned evil on his own.
** Enigma, the Riddler's Daughter, first started out as a member of the Teen Titans before switching to Deathstroke's Titans East. We were never shown Enigma's tenure as a hero, but we do know she joined Slade's group because he promised to help get her recognized by her supposed father.
** Jason Todd, the second Robin, became the murderous Red Hood after he was brought back from the dead, and constantly switched from an anti-hero to a straightforward villain.
** Addy Kane, Deathstroke's first wife, was driven insane by a blood transfusion she received from her husband, gaining his immortality and becoming the new HIVE mistress.
* Tigress in ''Young All-Stars'' after her death and resurrection at the hands of Gudra the Valkyrie, which was meant to explain her origin of becoming the Golden Age villain the Huntress.

'''Marvel'''
* ''ComicBook/AvengersArena'': [[spoiler:Apex is the only one of the kidnapped teens who is actually willing to play Arcade's game, killing Juston to steal his Sentinel, seizing control of Deathlocket and the Darkhawk armor with her technopathy to carry out her plans, and using the latter to kill Nico.]]
* From ''ComicBook/FantasticFour'', Sue Storm believe it or not. She once went mad and became a villain named Malice, who was hell-bent on killing her former teammates. When she recovered, this was one of the biggest contributions to her changing her name from the Invisible Girl to the more mature Invisible Woman and [[TookALevelInBadass Taking a Level in Badass]].
* In ''ComicBook/DarkReign'', ComicBook/TheSentry did this joining Norman Osborn's ComicBook/DarkAvengers in hope to getting cured from his SuperpoweredEvilSide, The Void. [[spoiler:In the end Osborn set a scheme in motion that made the Void take over completely.]]
* ''ComicBook/SpiderMan''
** Following the ''ComicBook/SuperiorSpiderMan'' arc, [[spoiler: Peter's former friend Liz Allan]] has been seen in a new alliance with Norman Osborn as he attempts to establish a new identity and corporation (now that his identity as the ComicBook/GreenGoblin is no longer a secret). Whether [[spoiler:she]] is doing this entirely out of free will is unknown, but it's very possibly that the biggest reason is [[spoiler:to ensure a better future for her son.]]
** Thanks to the actions of the ComicBook/SuperiorSpiderMan, the ComicBook/BlackCat, once one of Franchise/SpiderMan's closest allies, has gone from ClassyCatBurglar to aspiring crime boss.
* The UltimateMarvel
** ComicBook/{{Quicksilver}} started off as a baddie, but joined TheUltimates fairly quickly. This lasted until the death of his sister, the ComicBook/ScarletWitch, at which point he went back to villainy, ending up a member of the [[ComicBook/DarkAvengers Dark Ultimates]] [[spoiler: before his death.]]
** Though never particularly heroic or stable, the Ultimate [[Comicbook/TheIncredibleHulk Hulk]] joined him as a member of the Dark Ultimates as well.
** Ultimate Reed Richards became a villain as well after [[FakingTheDead faking his own death]]. He's now one of the [[BigBad Big Bads]] of the UltimateMarvel universe, and is intent on [[WellIntentionedExtremist forcibly remaking the world into a utopia]].
* ''Comicbook/{{X-Men}}'':
** Colossus, after his sister, Ilyana, died. It didn't last long.
** The longtime member Bishop - after years of looking for a mysterious traitor who was supposed to kill X-Men, he betrayed them himself, for the same reason he joined them in the first place - to stop a BadFuture from happening.
* In ''ComicBook/{{Runaways}}'', [[spoiler:Chase]] briefly went over to the dark side, attempting to form a pact with [[BigBad the Gibborim]] in an effort to resurrect [[spoiler:Gert]].
* During ''ComicBook/CivilWar'', the ComicBook/NewWarriors became pariahs after being blamed for a disaster that killed over a hundred people. One of their former members, Hindsight Lad, decided to turn on his former teammates, giving away their real names and addresses to the angry mobs in the hopes that he himself would be spared.

'''Other'''
* [[spoiler:Javi]] in ''ComicBook/{{Negation}}'' goes through this after [[spoiler:Charon brought him back from the dead and convinced him that his conquest of the Negation-verse and his pending invasion of the main Creator/CrossGen universe [[WellIntentionedExtremist was a good and necessary thing]]. Javi, a religious man who had questioned his faith even before his abduction to the Negation-verse, came to look upon Charon as a god, one in whom he could place his whole trust in, without question]]. He becomes a KnightTemplar as a result.
* In ''Comicbook/ArchieComicsSonicTheHedgehog'', the most notable thus far was Fiona, who turned against the Freedom Fighters in #172 and joined Anti-Sonic/Scourge in Moebius (formerly Anti-Mobius).
** Naturally, anybody who was [[UnwillingRoboticisation roboticised]] also pulled this, though [[CyberneticsEatYourSoul typically not of their own free will]].
** Espio turned against the Freedom Fighters and Chaotix to join the Iron Dominion, but returned. It turned out [[DoubleAgent to be a ruse]], but it wasn't exactly a harmless one.
** And before either of those two... Drago Wolf and Sleuth Dog.
** #178-179, though it could just be a political debate in which both sides use violence instead of words.
** [[spoiler:Geoffrey St. John]] appeared to have one in issues 219-220, but this is actually a subversion, as it was soon after retconed that he'd actually been working for Ixis Naugus since before either of them were even introduced, making him TheMole instead.
* [[spoiler:Daniel Cross]] in ''ComicBook/AssassinsCreedTheFall''.
* ''ComicBook/{{Irredeemable}}'' is based on this concept with the Plutonian, a Superman-esque character, snapping due to the pressure and becoming the ultimate villain.
* In ''ComicBook/AllFallDown'', [[spoiler:Pronto]] undergoes this in exchange for new legs as fast as his old ones.
* In ''ComicBook/SonicTheComic'', Nack the Weasel is introduced as a member of the heroic Chaotix - but by the end of their introductory story he's sold them out to the Brotherhood of Metallix, an army of spectacularly evil robotic copies of Sonic. Admittedly a loose example, as a) he'd clearly already turned before the story started and b) the character was always a villain in the Sonic games, so seeing him as a hero first is the unexpected bit.
* ''ComicBook/MyLittlePonyFriendshipIsMagicIDW'': [[spoiler:Rarity, who is kidnapped and subjected to MoreThanMindControl and DemonicPossession to become Nightmare Moon's successor.]]
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