* Hal Jordan, ''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/{{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. Now, they've very "cleverly" revealed that she was actually {{brainwashed}} by Comicbook/{{Deathstroke}} the entire time.
* [[{{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]].
** And her skirt was just as short as [[FanNickname Supertorso's]] "Belt with a trim" microskirt after the switch! Bad move all around... then the next outfit made it look good.
* In a particularly bad example of ExecutiveMeddling, DC planned to turn CaptainAtom into supervillain "Monarch." When readers guessed the plan ahead of time, they changed their minds at the last minute and made the character "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.
* ComicBook/TwoFace, in the Franchise/{{Batman}} comics (and later, ''Film/TheDarkKnight'') is a good-guy district attorney who turns into an evil criminal.
* [[Comicbook/{{X-Men}} Colossus]], after his sister, Ilyana, dies.
* 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.
* Mandrakk, the Dark Monitor from ''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 ''CrisisOnInfiniteEarths'' - is true, then this might be the ultimate FHT in comics.
* In ''ComicBook/DarkReign'' TheSentry does that, joining Norman Osborn's DarkAvengers in hope to getting cured from his SuperpoweredEvilSide, The Void. [[spoiler: In the end Osborn set a scheme in the motion that made Void take over completely.]]
* The UltimateMarvel {{Quicksilver}} started off as a baddie, but joined TheUltimates fairly quickly. This lasted until the death of his sister, the ScarletWitch, at which point he went back to villainy. He's currently a member of the [[DarkAvengers Dark Ultimates]].
** Though never particularly heroic or stable, the Ultimate [[Comicbook/TheIncredibleHulk Hulk]] joined him as a member of the Dark Ultimates as well.
* [[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 teamates. 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]].
** 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]].
* [[spoiler: Javi]] in ''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 has been 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.
* 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.
* 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 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.]]
* [[spoiler: Daniel Cross]] in ''ComicBook/AssassinsCreedTheFall''.
* {{Irredeemable}} is based on this concept with the Plutonian, a Superman-esque character, snapping due to the pressure and becoming the ultimate villian.
* In ''ComicBook/AllFallDown'', [[spoiler:Pronto]] undergoes this in exchange for new legs as fast as his old ones.
* A very big one few years ago was ComicBook/{{X-Men}} 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 ''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.
* In ''ComicBook/DeathOfTheFamily'', [[spoiler: Harley Quinn has gone from the SuicideSquad and joined up with the Joker. This is assuming that Suicide Squad can be considered Faces to begin with]]. She ends up back with the Squad once Joker is defeated, however.
* [[Franchise/GreenLantern The Guardians of the Universe]], having been SlowlySlippingIntoEvil ever since ''Rebirth'', finally crossed the MoralEventHorizon following the {{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/MyLittlePonyFriendshipIsMagicIDW'': [[spoiler:Rarity, who is kidnapped and subjected to MoreThanMindControl and DemonicPossession to become Nightmare Moon's successor.]]
* ''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.]]
* Thanks to the actions of the ComicBook/SuperiorSpiderMan, the Black Cat, once one of Franchise/SpiderMan's closest allies, is now one of his foes.
* The chief antagonist of ''ComicBook/TheMultiversity'' is a former "cosmic defender".
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