History FallenHero / VideoGames

** King William the Just was corrupted by the Blood Reaver into becoming a TinTyrant called The Nemesis. Kain travels back in time and kills William, but he is instead turned into an InspirationalMartyr. The mighty King is just an UwittingPawn no matter how his life turns out. Poor William, indeed.

* ''VideoGame/{{Warcraft}}'' is ''very'' fond of this trope.
** Sargeras in ''VideoGame/{{Warcraft}}'' originally fought demons for millennia, but eventually [[HeroicBSOD fell into thinking that it was no use and chaos was actually the only real solution to everything]]. Just to signify what this meant, [[EvilMakeover his bronze skin split apart, revealing a new body of fire and brimstone]].
** Archimonde and Kil'jaeden, the leaders of the eredar who sold their souls to Sargeras and became the leaders of the Burning Legion.
** Similarly, the human prince and paladin Arthas eventually resorted to the cursed blade Frostmourne to slay the demon that was (apparently) behind the plague that turned people into the undead. As a result, it took his soul and turned him into a death knight loyal to the Lich King (who [[MagnificentBastard had all that planned from the start]]).
** Then there's the death knights that followed him, which constitute Orders of Fallen Heroes. A force of them in ''Wrath of the Lich King'' are sent to wreak havoc in Northern Lordaeron... All of which seems to be little more than a [[spoiler:ploy to lure out Tirion Fordring, one the few living beings that could even be considered anything close to a threat to the Lich King. They were just a diversion and, eventually, as a result of a climactic battle in which Tirion reveals the truth of their betrayal and ultimate expendability]], pull a HeelFaceTurn. The player plays through this entire sequence, including all the irredeemable evil goodness inherent therein.
*** Sylvanas Windrunner was originally a good hearted, [[LovableAlphaBitch if rather vain]] defender of her homeland, not that unlike Arthas orginally was, she ended up being killed and turned undead when he invaded her homeland, and while turning undead didn't make her evil immediately like with him, by this point she is little better than the Lich King himself.
** And the night elf Illidan, trying to fight fire with fire (or demons with demon magic), eventually became a semi-demon himself.
** ''The Frozen Throne'' shows how the arrogant-but-decent high elves turned into the evil, demon-following blood elves they are in ''VideoGame/WorldOfWarcraft''.
*** In a desperate attempt to save his people, Kael'thas turned to demons, and let himself be consumed by their fel magic.
** Neltharion the Earth-Warder, one of the Five Dragon Aspects, charged by the Titans to protect the lands of Azeroth, DugTooDeep. After a little MindRape by the resident {{Eldritch Abomination}}s, he's calling himself [[NamesToRunAwayFromReallyFast Deathwing]].
*** Neltharion took every one of the black breed of dragons with him. They are hunted and mindlessly killed, sometimes just for sport. The truth is that they have all been driven completely insane and/or have lost every last one of their morals. The breed has almost been wiped out or forced under ground. It didn't help that Deathwing is dead, which probably just made things worse for the breed.
*** By that same token, Malygos the Spell-weaver, the Aspect of the Blue dragonflight. Best remembered from the pre-Sundering days for his playfulness and good humor, being the protector of magic. After Deathwing wipes out most of the blue dragons and seriously wounds Malygos, the latter spends 10,000 years in isolation, going mad from loneliness and betrayal. Despite snapping out of his madness in ''Day of the Dragon'' to help fight Deathwing and free Alexstrasza and the rebirth of the Blue dragonflight, Malygos never goes back to his cheery old self. Instead, he declares war against all non-dragon magic users, forcing Alexstrasza to assist heroes in killing a fellow Aspect.
** The Scarlet Crusade, which started out fighting to protect humans from the Scourge in Lordaeron, and gradually became increasingly paranoid to the point that anyone not a Crusader was deemed tainted. [[FromBadToWorse Then their leader was outright corrupted by the undead.]]

* Jack Krauser from the ''Franchise/ResidentEvil'' series qualifies as such, especially when ''[[VideoGame/ResidentEvilTheDarksideChronicles Darkside Chronicles]]'' paints him with an initially heroic light, but after his arm was heavily injured (which resulted in him being fired from SOCOM due to it never recovering), as well as becoming increasing envious towards Leon, he eventually fell to the depiction of him in ''VideoGame/ResidentEvil4''.

* Jack Krauser from the ''Franchise/ResidentEvil'' series qualifies as such, especially when Darkside Chronicles paints him with an initially heroic light, but after his arm was heavily injured (which resulted in him being fired from SOCOM due to it never recovering), as well as becoming increasing envious towards Leon, he eventually fell to the depiction of him in ''VideoGame/ResidentEvil4''.

* The [[Franchise/{{Injustice}} Injustice-verse]] version of [[Characters/InjusticeSuperman Superman]] is this in ''VideoGame/InjusticeGodsAmongUs'' and it's sequel ''VideoGame/Injustice2''. The Joker tricks him into killing Lois Lane and their unborn child by dosing him with a Kryptonite-induced variant of Scarecrow's infamous fear toxin that made him hallucinate Lois as Doomsday, setting off a nuke on a DeadMansSwitch that the Joker had rigged that devastates Metropolis and kills millions, and leading to Superman killing the Clown Prince of Crime in a fit of rage. And then it just goes downhill from there as he basically takes over the world in order to make it a better place, killing criminals and even a few heroes as he falls deeper and deeper into the abyss. Several other heroes join his crusade including Wonder Woman, Flash, Green Lantern, Shazam, and even some villains join such as Sinestro, Killer Frost and Black Adam. He ends up doing some truly despicable things such as [[spoiler:killing Shazam in a slow and painful fashion]] when he dares bring up that Supes has gone too far.

* Jon Irenicus from ''VideoGame/BaldursGateII'' counts. Prior to his exile from [[spoiler:Sulldanesselar]], he was an upstanding citizen and powerful mage. Pride was his downfall; he was exiled and [[spoiler:stripped of his soul]] for using his power to try and achieve godhood.

** On the Crimson Flower route, Dedue [[spoiler: hands out Crest Stones to random Kingdom soldiers, transforming them into Demonic Beasts,]] which would mean having to put them down even in a victory scenario. [[spoiler:He later does it to himself, although if the player is fast enough, they can take him out before he transforms.]] If not recruited, Sylvain and Mercedes [[spoiler: are complicit in this plan,]] the former even voicing his ''approval'' of it for the sake of revenge [[spoiler: when the first soldier turns if the player killed both of his {{Childhood Friend}}s Felix and Ingrid on the previous map]].