When a villain's origin involves the character (previously outwardly normal) suddenly flipping out and killing a large number of people in a single incident. Bonus points if any of these circumstances apply:

# The villain was [[EnfanteTerrible just a kid at the time]].
# The people killed included [[SelfMadeOrphan the villain's family]].
# The villain had [[ForTheEvulz no real reason to do this]].

See also WhereIWasBornAndRazed. If the villain's origin involves a ''literal'' bath in blood, see BloodBath.

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!!Examples:

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[[folder:Anime & Manga]]
* ''Manga/{{Naruto}}'' has Zabuza (1,3), Itachi (1,2, apparently 3 at first), Hidan (3, probably 2), Kakuzu and now Sasuke (1,2).
** [[spoiler: After seeing his teammate and love interest Rin brutally stabbed by Kakashi, the very friend he had asked to protect her with what he thought was his dying breath, [[FallenHero Obito Uchiha]] loses it in a violent and brutal display of primal fury and goes about slaughtering the enemy ninja who drove Kakashi into that position in the first place. Thus opening the path to his career as [[MalevolentMaskedMan Tobi.]]]]
* ''Manga/FullmetalAlchemist 's'' AntiVillain [[spoiler:[[HeelFaceTurn turned]] AntiHero]] Scar begins his serial-killing career by killing any and all available Amestrians -[[spoiler: after waking up in a hospital to find that his entire family has been killed by the State Alchemist Kimblee and that his [[BadassTransplant brother's arm has been grafted onto his body]] in the place of his own severed arm.]] He [[BerserkButton flips out]] and starts his rampage with the two Amestrian doctors who saved his life. [[spoiler: Who are married. And who also happen to have a daughter who'll grow up to become a pretty good [[WrenchWench automail mechanic]]. OhTheHumanity!]]
* [[YuYuHakusho Sensui's]] StartOfDarkness was like this: he [[GoMadFromTheRevelation flipped out]] upon learning HumansAreTheRealMonsters, and killed everyone in the Black Black Club's villa.
** Coincidentally, the people he murdered were themselves enjoying a demon blood bath.
* There's quite a few sympathetic starts of darkness in RurouniKenshin, but the one closest to this trope is when [[StepfordSmiler Seta Soujirou]] murders his abusive relatives after they pushed him one time too many and ended up as TheDragon for a SocialDarwinist.
* Sometimes the bloodbath happens because [[BewareTheNiceOnes the person in question got pushed too far and snapped out]]. Just take a look at Lucy from ''ElfenLied'' and what she did to the [[KidsAreCruel cruel kids]] in her backstory for beating the puppy that she'd started caring for to death.
** Bonus point #1, minus points for having two separate flip-out incidents before it became a habit.
* Alas, poor [[GaReiZero Yomi]]... (2, and when she's lost it, 3)
* Rob Lucci of ''Manga/OnePiece'' is a perfect example. His first mission as a [=CP9=] agent was given to him when he was only a kid; to save some hostages from pirates... he killed not only the pirates, but all the hostages as well, because they were getting in the way/didn't deserve to live. And he got a nasty-looking scar on his back in the process, which coincidentally looks like the World Government flag.
* Tongpu, a.k.a. Mad Pierrot from the ''CowboyBebop'' episode "Pierrot Le Fou."
* While the extent of her evil is ''[[NobleDemon very]]'' debatable, [[TheArchMage Evangeline]] [[UndeadChild McDowell]] from ''Manga/MahouSenseiNegima'' is convinced that she underwent this. Extra credit though for having all three points getting hit. She had just turned 10 when it happened. It is implied but not outright stated that she killed her family, and she had no reason to do so. Though it is heavily implied she was either not in control of herself when it happened or she wasn't conscious of it and only realized it happened after it happened.
* An '''extreme''' example occurs in Literature/ShinSekaiYori. The anime deals with a new age of mankind in which humans have developed telekinetic abilities. Unlike most anime of this genre, this anime explores the more realistic possiblities that could happen if even just one person develops such powers. Boy K (no real name given) seemed to just be a quiet child, but psychological exams revealed disturbing [[TheSociopath sociopathic]] tendencies. No one knew what to do with him, but they waited too long. Eventually, in the middle of class, Boy K let go of his humanity and ''tore his teacher apart limb from limb''. He didn't stop there. He went on a full out rampage. Boy K slaughtered over 1,000 people ''on the first day '''alone'''''.
* VillainProtagonist [[LightIsNotGood Light]] [[MagnificentBastard Yagami]] of ''Manga/DeathNote'' takes his first step into corruption and madness when he goes on a massive killing spree after receiving the [[ArtifactOfDeath Death Note]]. Of course, he is not a little kid at the time (he's [[TeensAreMonsters seventeen]]), he doesn't kill his family ([[spoiler: at least, not then]]), and he has a number of reasons for doing so (mostly because he's bored, disillusioned, and insane). That first week racked up a body count of five hundred.
-->'''Ryuk:''' ...[[DeadpanSnarker You've taken quite a liking to it]].
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[[folder:Comic Books]]
* [[BewareTheSuperman The Plutonian]] from ''ComicBook/{{Irredeemable}}'' kicked off his reign of terror by leveling his patron city and massacring the inhabitants.
* He's actually the protagonist (one hesitates to say "hero") rather than the villain a lot of the time, but {{Lobo}}'s origin story involves him killing off his entire ''race'' except for himself, because he was dissatisfied with the grade he received on a school project. Played for laughs, since Lobo was originally intended as a deconstruction of the whole [=GrimDark=] Anti-Hero fad of the 1990s.
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[[folder:Fan Works]]
* In ''FanFic/TheJadedEyesSeries'' Harry snaps and murders the Dursleys when he's six years old.
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[[folder:Films -- Animation]]
* ''WesternAnimation/MonstersVsAliens'': Although we don't hear all of Gallaxhar's back story, he does directly state that he was the one who [[EarthShatteringKaboom blew up his planet]].
* ''WesternAnimation/KungFuPanda'': Depending on [[BloodlessCarnage how much]] damage you think he did (it's ambiguous), Tai Lung when he learned he would not be the Dragon Warrior.
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[[folder:Films -- Live-Action]]
* The original [[Film/{{Halloween 1978}} Halloween]] is one of the greatest, most notorious examples of this trope across all media, playing it entirely straight and fulfilling all three conditions. Michael suddenly flipped and, for no good reason, killed his older sister. Eventually, Dr. Loomis concludes that there's nothing to him, except evil.
** The [[Film/{{Halloween 2007}} remake]], however, is a subversion, since it tries to give Michael a FreudianExcuse.
* In the ''StarWars'' prequel trilogy, Anakin Skywalker's StartOfDarkness (murdering a camp of Sand People) and later his attack on the Jedi Temple. The slaughter of the Tusken Raiders was because they tortured and killed his mother.
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[[folder:Literature]]
* ''Literature/HarryPotter'':
** Sirius Black killing a bunch of innocent bystanders [[spoiler:is a subversion, as it was Peter Pettigrew who didso and for whom this trope does apply.]]
** [[spoiler:Tom Riddle]] when he murdered his father and grandparents.
* In the StarWarsExpandedUniverse, the origin story of Palpatine/Darth Sidious involves him throttling his family and their bodyguards to death, and intending to at the very least kill his father since he was born due to hatred of him, and for no reason other than his family forbidding his contact with Plagueis, as revealed in ''DarthPlagueis''.
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[[folder:Live-Action TV]]
* The ''Series/CriminalMinds'' episode "Haunted" begins with a man having a psychotic break at a pharmacy and killing a number of the other customers.
* [[spoiler: Rumpelstiltskin]] in ''Series/OnceUponATime'' goes on a killing spree after suddenly acquiring awesome powers. Justified by the fact that they were all soldiers trying to conscript his barely 14 year old son, and he was trying to protect the kid - but he was still evil, since the power was dark and corrupted him.
* When ''Series/{{Angel}}'' first became the vampire Angelus, he proceeded to kill every single living person in his village, including his family.
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[[folder:Tabletop Games]]
* TabletopGame/ForgottenRealms: Sammaster's fall started in somehow similar way - he blasted slavers with spells, but in process also caused the deaths of the very people he tried to rescue. Not that he was the shining example of mental stability before this.
* In TabletopGame/{{Warhammer}} Fantasy Battles, one of the named chaos villains used to be a shaman's apprentice, the weaker of two twins, constantly bullied and ridiculed for his weakness. When his prayers attracted attention of Chaos god Tzeentch, he was granted powerful magic as well as a powerful body to match (he was magically grafted on top of his brother's shoulders) His first act was to turn his power against the tribe, making the village "run with molten flesh".
** That's Vilitch the Curseling, in case you're wondering. One rendition of Archaon's backstory relates that after having been driven insane by what he read in the Book of Necrodormu, he then slaughtered his family in cold blood before fleeing to Norsca.
* ''TabletopGame/{{Warhammer 40000}}'' has Angron who had tragic story in his descent to evil. He was once a gladiator slave who along his fellow gladiators fought their way out to freedom against their Nucerian slavers. The Emperor sought him to join his crusade, but Angron refused, choosing to stay and die along side his brethren who are about to be cornered by the Nucerian armies. The Emperor then teleported Angron alone into his ship, leaving his fellow warriors to be slaughtered by the Nucerians. Angron never forgave the Emperor for what he did, when he became Primarch of the World Eaters his legion became the most brutal of them all, when Horus turned to Chaos he was one of the first Primarchs to join him, and soon became a Daemon Prince of Khorne.
** Indeed, when Angron was found by the slave traders who eventually sold him to the gladiatorial arena, he was naked, drenched in gore, and surrounded by the corpses of the Eldar assassination squad he'd butchered in self-defense when they attempted to murder him to pre-empt his falling to Chaos. Did we mention he was just a little boy at the time?
* ''Very common'' angst-oriented origin story for both good and evil Werecreatures in ''TabletopGame/WerewolfTheApocalypse''.
** A tradition continued in ''TabletopGame/WerewolfTheForsaken'', which, if anything, enforces the "don't forget that you're playing a monster" thing more harshly than its predecessor. The books make it quite clear that, if you're a Rahu (warriors who changed under the full moon), your First Change most likely involved someone dying horribly.
* ''TabletopGame/EclipsePhase'' includes "The Lost Generation", an attempt at accelerated maturation GoneHorriblyWrong that are all assumed to be this. Several of the survivors of the program ARE this, but not nearly all of them.
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[[folder:Video Games]]
* In ''[[VideoGame/FirstEncounterAssaultRecon FEAR]]'', Paxton Fettel fell into this trope as a kid during the so called "synchronicity event", during which he was possessed by Alma and killed several scientists using his psychic powers.
* In ''VideoGame/FableII'', if the player feels so inclined, after getting a sword they can slaughter the gypsies who raised them as a nice little warm-up before carving a bloody swath across Albion.
* ''VideoGame/FinalFantasyVII'': Sephiroth and his infamous massacre at Nibelheim.
* ''VideoGame/FatalFrame'': [[spoiler:Kirie and the Himuro Family Head, Sae and Reika. All save Himuro resulted directly from a botched sacrifice, and Himuro got the curse second-hand. They all suddenly engaged in mass-slaughter, their victims becoming enraged, vengeful ghosts themselves who continued to claim victims decades or even centuries after.]]
* So how does ''VideoGame/SoulNomadAndTheWorldEaters'' infamous [[VillainProtagonist Demon Path]] begin? [[WhereIWasBornAndRazed By killing everyone in your village, of course.]]
* In ''VideoGame/{{Valis}} II'' (Japanese computer version), the origin story of Cruel King Megas is that, after being exiled by his kingly father, he returned to slaughter his entire family, tearing his brothers to pieces and eating his mother. Only his father's HeroicSacrifice, turning him into a SealedEvilInACan, prevented further bloodshed... until the seal was broken.
* {{Trauma Team}}'s CR-S01 unleashed a bioterrorist attack that killed everyone in Cumberland College, but with a twist - he has no memory of how or why he did it. [[spoiler:It turns out that he was actually framed by his adoptive father Albert Sartre.]]
* ''VideoGame/SuikodenIV'' has Graham Cray, who is considered responsible for the destruction of his hometown in a Type 2. [[spoiler:In reality, it was his son who fatally unleashed the full power of the Rune of Punishment against soldiers running a FalseFlagOperation. Becoming TheScapegoat on top of everything else just drove him into villany.]]
* Most of the cast of ''TwistedMetalBlack'' has this as their backstory.
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[[folder:Visual Novels]]
* Joe Darke in ''Franchise/AceAttorney'', a businessman who panicked after accidentally running over a man with his car and started to kill the witnesses of the accident (and the witnesses of ''those'' murders too).
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[[folder:Web Comics]]
* Helen Narbon in ''Webcomic/{{Narbonic}}''... insofar as she can be considered a villain. Apparently all mad scientists try to cause as much carnage as possible when they [[WithGreatPowerComesGreatInsanity go mad and get full control over their mad science abilities]]. Some of them were already evil before they were mad.
* They aren't all ''necessarily'' villains in the normal sense, but most times the first notice the world has of a new "Spark" (mad scientist) in ''Webcomic/GirlGenius'' is the total depopulation of some village, usually that of the Spark.
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