Genocide from the Inside

The Blacksmith: Tiger style? I thought your clan was extinct.
Brass Body: My clan is extinct. Because I killed them.

— The Man with the Iron Fists

Essentially Self-Made Orphan on a larger level, this is when a person is responsible for the death and destruction of their entire people. Likely to be part of a Bloodbath Villain Origin, and the one who does this often turns out to be a budding Omnicidal Maniac or a Straw Nihilist. Don't be surprised if There Is Another from the group who survives and looks to settle accounts somewhere down the line.

Similar to Hunter of His Own Kind, but tends to differ on several counts, including that Hunter of His Own Kind tends to be an ongoing trope currently in effect, with few if any signs that they will ever succeed in largely wiping out their own kind. (Also, they may simply be hunting evil members of their own kind or even an Evil Counterpart Race.) Like that trope, the slayer can be portrayed as quite differing degrees of depraved, himself, depending on just how bad his people were — or in some cases even heroic, if they were really, truly irredeemably evil, monstrously inhuman or otherwise completely unsympathetic. In any case, with this trope, the person carrying out the genocide has already succeeded and whatever is left of their people, if anything, is a tiny remnant at best.

See also Sole Survivor, Last of His Kind, Antagonistic Offspring. Often overlaps with Self-Made Orphan and/or The Purge. Compare and contrast with Hunter of His Own Kind, Boomerang Bigot, Where I Was Born and Razed, and Category Traitor. A subtrope of Murder in the Family.

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Examples:

Anime & Manga

• This turns out to have been attempted in Promare, when it is revealed that Kray Foresight, who intends to use the entire Burnish population as a fuel source to power his Colony Ship (in a process that would kill all of them), is a Burnish himself. Fortunately, his plot is averted by the end of the film, with the entire Burnish population including Kray himself merely being depowered rather than being killed outright.
• In Naruto, we know from the start that Sasuke's older brother Itachi did this to his clan many years ago, sparing only Sasuke. Only much later do we find out why: Itachi was under orders to do so from Konoha (mainly Danzo), as his clan was planning a coup. And even then, Itachi didn't kill most of the clan — Obito did. Obito was also the one who manipulated the circumstances that led to them planning the coup in the first place, engineering their demise.
• In Samurai Champloo, soldiers of the Matsumae domain sent to arrest the Ainu warrior Okuro believe that he did this to his own clan and also killed samurai from their clan. The truth is that Okuro's clan was wiped out by disease and he attacked the samurai because he saw them burning the village to prevent the disease from spreading rather than trying to save the people.
• Kars the Pillar Man from JoJo's Bizarre Adventure: Battle Tendency practically wiped out his own race when they opposed his goal of elevating their already powerful race to Ultimate Lifeform limits. He only spared his loyal follower Esidisi and two infants he would raise to become his servants.
• Eneru from One Piece destroyed his homeland, Birka, after getting his Shock and Awe powers.
• Wavess, the first major enemy of the Shonen Jump manga Stealth Symphony, proves to be this. She killed half the population of her mermaid tribe and sold the other half to the very pharmaceuticals that experimented on her and gave her power over liquid because she was angry that at how happy they were at the chance for some revenge when she was the one with the power.
• Fujimoto from Ponyo on the Cliff by the Sea aspires to this — also overlaps with Kill All Humans and Transhuman Treachery.
• During the Future Trunks' Saga in Dragon Ball Super, Future Zamasu and Goku Black, who are the same person, are revealed to have singlehandedly slaughtered all of the other Kais in the twelve universes to keep them from stopping their plan to slaughter the mortal races. Despite the fact they wanted to rid the multiverse of the mortal races to let it be a paradise for the gods, they really didn't seem to have a problem with being the only gods to enjoy it.
• Attack on Titan:
  • The King's Will implanted into the Founding Titan is one half of a scheme between Karl Fritz and the Tybur Clan to eventually wipe out of their own people. King Fritz implanted his Will into the Founding Titan so that none of his successors could use its power to prevent the eventual genocide of the Eldian people. Meanwhile, the Tybur Clan ruled over Marley from the shadows while all other Eldians were thrown into concentration camps and used as military fodder. Eren presents the first opportunity in a century to escape this fate. Unfortunately, Eren decides the only way to do this is commit genocide on everyone else.
  • Zeke Yaegar's ultimate goal is to sterilize anyone who can be mutated into a Titan (including himself), so the cycle of persecution and giant monsters will finally stop. Unfortunately, while this would be much quicker and bloodless than Karl Fritz and the Tybur Clan's plan, this still includes the main cast and an entire race.
• Tweeny Witches: The military dictatorship of the warlocks have turned the wizards, the traditional subgroup of their own people, into a Dying Race in the present, something Wil laments to Arusu.
• Some years after World War II in Himenospia, a Japanese girl was stung by a "red wasp" and turned into a Queen-ranked mutant. She instinctively understands the purpose of her new brainwashing abilities and guesses the Allied Forces won the war because an older and more experienced Queen is the Shadow Dictator of America, so she forces her abusive parents into a murder suicide and gets rid of every other relative to conceal her own existance.

Comic Books

• Lobo the Czarnian killed the rest of his race with a biological weapon. As a high school science project. He gave himself an A.
• Thanos killed most of the other Eternals of Titan, his brother Starfox was one of the few survivors.
• Indirectly done by Marvel Comics' Impossible Man, who convinced Galactus to devour his own planet instead of Earth, killing all the Popuppians (except himself) in the process. They didn't mind.
• The ultimate goal of the somewhat terrifying Magnificent Bastard/Villain Protagonist Billy Butcher from The Boys is to kill everyone with Compound V in their system, thus ridding the world of supes altogether. It doesn't matter that Billy himself or all his best friends have been injected with Compound V, or that at this point so much of the world's population has been exposed to it that it's essentially become part of life in that world, Billy still is working towards that goal. Ultimately, he nearly goes through with it, and only the fact that he doesn't really want to kill all the people who've been unknowingly exposed to Compound V or his Morality Pet Wee Hughie stops him.
• Martian Manhunter's insane brother created a psychic plague that killed all the Martians. J'onn only survived because he did the psychic equivalent of cutting off an arm by severing his link to other Martians.
• In Annihilation, Stardust gives up the last remnants of her entire race of celestial beings to Galactus to eat.
• Shakara: Cinnibar Breneka, the noble founder of the Shakara Federation, is responsible for its destruction when he united the Shakara's enemies to wipe out his brethren with a Synthetic Plague and destroy his own homeworld.
• X-Men:
  • Attempted by Cable's Evil Twin Stryfe with his release of the Legacy virus, a Synthetic Plague specifically engineered to target and kill mutants.
  • Crisis Crossover villain Onslaught also tried his hand at this, deciding that he was wrong about being a Super Supremacist and that mutants deserved extinction just as much as humans after reading the memories of Nate Grey the X-Man. Like Stryfe, he was ultimately unsuccessful, but not for lack of trying.
  • With just three words, "No More Mutants" the mutant Scarlet Witch managed to reduce the mutant population from somewhere in the millions to little over 200. Some were depowered, some were killed (mostly due to their powers being vital to them) and the damage was not restricted to their home dimension, it was OMNIVERSAL.
  • Moira X, a mutant whose ostensible goal was to use her time-looping powers to create the best possible future for mutants, turns out to have secretly been plotting to find a way to eradicate the X-Gene entirely, rendering mutants unable to breed true and thus reducing them to a mere generational "blip" in the story of humanity, whom she views as the only race who deserves to rule Earth. When she is exposed, she is cast out from mutant society, and only the fact she has been Depowered and is thus human by their laws prevents them from executing her.
• When Paul Kupperberg's run on Doom Patrol brought back the villain Garguax, the alien reveals that he's destroyed his homeworld and is now the last remaining member of his race.
• Superman: Earth One: This continuity establishes that General Zod caused the destruction of Superman's home planet Krypton, in the present time intending to finish the job by killing Superman, who is his nephew in this version.
• Legion of Super-Heroes: Mano of the Fatal Five used his deadly touch to destroy his own home planet Angtu and wipe out the rest of his kind.

Fan Works

• In the Pony POV Series, it's eventually revealed that Lord Tirek came to believe that his species had become weak and soft. So his first atrocity upon getting his power was to wipe out his own kind out of disgust.
• In The Bridge (MLP), the albino Hyper Gyaos is forced to kill the rest of her kind in self-defense when the scent of her wounds drives them into a bloodlust and they try to eat her.
• Becoming a True Invader:
  • As she's leaving Fefa, Kor leaves behind bombs that neutralize her people's Healing Factor before causing them to explode. However, this is subverted in the long run, as it turns out they all eventually recovered from this.
  • Tak has no problem helping the Employer conquer and obliterate the rest of the Irken race.
• The Amazing Spider-Luz in: Across the Owl-Verse!: Belos and Bill of the Titan Trappers are both in contact with a voice that claims to be both the Boiling Isles Titan and the "Grand Hunstman" that the latter group worships, saying that it led the Trappers in eliminating the other Titans to protect the early witches societies from them after the other Titans grew jealous of their friendship with said witches.

Films — Animated

• Monsters vs. Aliens: Gallaxhar destroyed his own planet. He starts to explain why, but the cloning machine he's on keeps cutting him off.

Films — Live-Action

• Late in The Man with the Iron Fists, Implacable Man mercenary Brass Body reveals that he originally was a member of yet another animal-themed clan from Jungle Village, but that he wiped out his own clan years ago.
• Attempted in Who Framed Roger Rabbit which has Judge Doom trying to wipe out all the Toons and literally erase them and their home of Toon Town from the face of the Earth with "Dip" despite being a Toon himself.
• Loki attempts this in Thor because his adopted parents let him think his species was a bunch of monsters and then admitted he was one of them at the exact wrong time. There are also "Well Done, Son" Guy overtones of his attempting to show that he is a "true son" of Odin.
• In the Star Wars movies, the former Jedi Darth Vader played a large part in the elimination of virtually all Jedi from The Empire.
  • His grandson Kylo Ren hoped to pick up where he left off, whether by murder or conversion.

Literature

• The Elric Saga: In the short story, The Dreaming City, Elric leads an attack on Imrryr, the capital of Melnibone, of which he is the rightful emperor. The attack not only leads to the death of the city and its people, but also the one thing Elric actually wished to save from harm: Cymoril, his betrothed.
• In The Crystal Star, Hethrir, a Dark Jedi trained by Darth Vader, glassed his own homeworld and had the survivors turned into Human Popsicles in an attempt to curry favor with his master.
• Darth Bane: The titular Sith Lord believes the Sith Order should only have one master and one apprentice, so he orchestrates the destruction of everyone but himself and Zannah.
• In the Myst novels that reveal the backstory of the D'ni people, Veovis and A'Gaeris unleash a plague that wipes out most of the underground city's population and follows its refugees into other Ages, bringing down their civilization.
• In The Dresden Files book Changes, the half-vampire Martin is a triple agent who pulls a complex Thanatos Gambit to ensure his Red Court vampire masters will be annihilated by Harry Dresden. The motives are complex, but boil down to "I've had centuries to learn that my god-emperor and his leech-spawn just plain suck."
• In The Magician's Nephew, Jadis the White Witch, the Big Bad from the first The Chronicles of Narnia book, is revealed to have cast a spell that killed everyone on her world except her when she was on the edge of losing a civil war.
• A rare justified example in I Have No Mouth, and I Must Scream, in which the protagonist kills all the other surviving humans; there were only five of them left anyway. Not to mention, leaving them alive was a Fate Worse than Death, which they'd been suffering for centuries.
• In the Garth Nix short story, "Peace in our Time", it's gradually revealed that this is how Ahfred Progressor III, formerly the most powerful man on Earth, came to be living all alone in a small cottage with no visitors for the last ten years. He deployed massively powerful weapons against the entire world so he could finally get some peace and quiet.
• In Summer in Orcus, the villain Zultan Houndbreaker is notorious for his genocide of a peaceful and enlightened race of anthropomorphic Dogs, which he commemorates by wearing a helmet shaped like the head of a snarling hound. Near the end of the story, it's revealed that the dog-shaped helmet also disguises the fact that he is a Dog himself.
• Chronicles of Ancient Darkness: As soon as Eostra became the Eagle Owl Mage, she carried out a forbidden rite by bringing to life a ten-year-old Eagle Owl boy who had died in a rockfall. All the other Eagle Owls died out of sickness soon after, making Eostra responsible for her clan's demise. Thiazzi the Oak Mage is also the last of his clan, though it's unknown if he's directly responsible for their extinction.
• A Song of Ice and Fire: After his fiancee was abducted by Rhaegar Targaryen and died under questionable circumstances, Robert Baratheon became a fierce crusader against the remnants of House Targaryen, approving the brutal murders of Rhaegar's children and sending an assassin to kill Rhaegar's pregnant teenage sister. Yet Robert was able to reign on the Iron Throne because of his Targaryen ancestry; his grandmother was a Targaryen princess, and House Baratheon themselves are distant descendants of Aegon I Targaryen, the founder of the Seven Kingdoms.

Live-Action TV

• In Battlestar Galactica (1978), this is Baltar's endgame. He is a human who is a high ranking Cylon controller, and the Cylons are after the complete destruction of the humans. Note that this is a bit of a retcon from the original Battlestar Galactica movie; in that one Baltar, having betrayed humans to the Cylons in exchange for them guaranteeing the safety of his own world and his dominion over it, is summarily executed by the Cylons because their plan is to extinguish all humans.
• In Battlestar Galactica (2003), John Cavil, the oldest member of the second generation of Cylons, has committed genocide so frequently that he approaches Omnicidal Maniac territory. He not only started the war of extermination against the humans but has wiped out more than half of his own race. He destroyed all the Daniel copies out of jealousy by poisoning their embryonic chambers as the clones were being developed. When a civil war breaks out among the Cylons, he pretends to desire a settlement, only to betray the other faction and resorts to wiping out all the Sixes, Twos, and Eights (minus Boomer) still in existence.
• Doctor Who:
  • Davros arranged for the destruction of his own people, the Kaleds, by their mortal enemies, the Thals, when the former tried to stop his experiments.
  • The Doctor seemingly blew up his own planet during the Time War in a last-ditch attempt to save the universe not only from the enemy Daleks but also the increasingly destructive actions of his own people, the Time Lords. Thanks to the Timey-Wimey Ball this is actually Subverted. He didn't kill anyone, he simply thought he did, but actually sent the Time Lords to a pocket dimension.
  • In "Journey's End", Dalek Caan manipulates the Doctor into causing the total destruction of the Daleks (for a while) after a trip through the time vortex forced him to have a Heel Realization.
  • "Spyfall" ends on the reveal that the Master has done this, leaving him and the Doctor as the Last of Their Kind (again). His stated reason for doing so is because he discovered an Awful Truth about the history and origins of the Time Lords and felt he had to make the others "pay" for their lie, but he refuses to tell the Doctor exactly what he found out because he doesn't want to "make it easy" for her.
• Kamen Rider Drive has this in the form of Medic. Upon gaining the title of "Grim Reaper", she began silently exterminating Roidmudes who either act ruthlessly or act outside their jurisdiction. She eventually concludes that only a select few of the Roidmudes including herself and Heart should live. However, Heart stops her and reminds her that they're already a dying race with the Kamen Riders killing their kind.
• Celebro from Ultraman Z loves to use this trope via Grand Theft Me. He'll take over a member of a race, help advance their weaponry against hostile monsters, then use the weapons he helped them develop to wipe out all life on the planet. Fittingly, he calls it the "Civilization Self-Destruction Game" when explaining his true ambitions to Yoko Nakashima.

Podcasts

• According to episode 76.1 of Comedy Bang! Bang!, this is what Legend Of The Guardians The Owls Of Ga Hoole is about.

Tabletop Games

• In the Ravenloft module Curse of Strahd, Strahd von Zarovich's chamberlain Rahadin pulled this twice on his own people, the Dusk Elves, at the orders of Strahd. First he betrayed his original ruler Prince Haramun in favor of Strahd and his father Barov when their lands were conquered and was made an honorary member of the royal family in return, and then years later after Strahd's would-be-bride Patrina was stoned to death by her own people before she could marry him Rahadin was ordered to hunt down and execute every female Dusk Elf so what remained of his race would die a slow death by being unable to breed.
• Dark Sun: The villain responsible for turning Athas into the Crapsack World it is now is Rajaat, a member of a race called pyreens. He was motivated by a desire to return Athas back to the age when there was only one race, which would mean killing off all the other races including his own since the pyreens weren't the original race. He manipulated humans into a genocidal war against the other races, planning to eventually betray and wipe them out too since it turns out humans were not the first race either.
• Warhammer 40,000: Khârn the Betrayer got his nickname during the Horus Heresy when he and his fellow World Eaters (an entire Chaos Space Marine Legion of berserkers) were fighting the Emperor's Children (another Chaos Space Marine Legion of Fighting Narcissists and Combat Sadomasochists) on the frozen world of Skalathrax. Due to nightfall and the oncoming subzero temperatures, both sides stopped fighting to take shelter. Khârn took offense at this and ran around with a flamer torching every shelter, World Eater and Emperor's Children he could find to force them to fight to the death, singlehandedly destroying both Legions' ability to be a self-sufficient force and reducing them to small mercenary warbands. Note that despite the nickname, Khârn was entirely in the right according to the precepts of his god: Khorne demands bloody self-sacrifice from all his followers, and to cease fighting for so pitiful a reason as "it's too cold" made them worse than heretics.
• Warhammer: Nagash the Great Necromancer was born as a prince of Nehekhara's greatest city, Khemri, and personally saw to the annihilation of his entire civilization by magical plague and undead nightmare creatures, all because he had waged a ruthless war of conquest against his rebellious people and lost.

Toys

• BIONICLE: Once Makuta Teridax took over Mata Nui's body, one of the first things he does is destroy all surviving Makuta, except for Miserix, who he kept alive just to torture. Before that he also sent several Makuta, including one of his most fanatically loyal followers, to die in Karda Nui by failing to inform them that Karda Nui would turn into a death trap during Mata Nui's awakening.

Video Games

• In Cyberpunk 2077, one of the ending paths reveals that this is the plan of Yorinobu Arasaka, the closest figure the game has to a central antagonist. When confronted at the end of the game his stated goal is to destroy the Arasaka Corporation by running it into the ground via killing off the Board of Directors and waging an unwinnable world war.
• Seath the Scaleless from Dark Souls was born an abomination without the scales that granted the other dragons immortality. Out of jealousy, he betrayed his own and sided with Lord Gwyn in the war against his brethren, leading to the extinction of the Everlasting Dragons.
• In the backstory of the Darksiders games, the Nephilim had no place to call their own in Creation. This angered them so much that they decided to take Creation for themselves and began a universal campaign of destruction. Four of the Nephilim eventually turned against this course of action and killed off the rest of the Nephilim as their first mission for the Charred Council. These four Nephilim would become the Four Horsemen. This is mainly explained in Darksiders II, which also deals with the fallout of the Horsemen's decision. Namely in the form of the Nephilim's progenitor Absalom, who became the source of the Corruption that serves as the primary threat Death (who betrayed his brother and lead the Horsemen into their rebellion while ironically being the only one who still feels guilty about the whole thing) faces in the game.
• In Fallout 2, the Enclave is intent on releasing a modified version of the FEV virus into the wasteland, which will wipe out all 'mutants' and leave the 'pure' humans of the Enclave the only survivors. The scientist responsible for this project, Charles Curling, can be talked into realizing this plan is monstrous and insane, after which he will release the virus within the sealed environment of the Enclave Oil Rig, wiping out his own people so everyone else can live.
• Seox from Granblue Fantasy as his backstory. He was an incredibly talented assassin in his clan, and as a result was incredibly feared by them to the point where the clan had some dissenters planning to get rid of him. His family isolated him and his father even disowned him, which drove him to eventually kill the entire clan in rage and anguish.
• In the evil ending of inFAMOUS: Second Son, Delsin returns home with his concrete powers to save the rest of the Akomish tribe, only for the tribe to reject him. Having seen his rampage through Seattle on the news, they now view him as a disgrace to the tribe, and would rather die, taking their culture with them, than be saved and owe their lives to a raging psychopath. Furious at their rejection, Delsin eagerly helps them along to their deaths by planting an Orbital Drop on the Akomish longhouse.
• Kingdom Hearts:
  • This is Jafar's ultimate goal for Agrabah. After succeeding in conquering the world, capturing Jasmine, and obtaining the Magic Lamp, he makes his first wish to reveal the Keyhole, which will allow the Heartless under his command to enter and take its heart. Had Sora not arrived in time, Agrabah would've been destroyed and everyone on it killed.
  • In the same game, Ursula makes a similar attempt to destroy Atlantica. Unlike Jafar, she can't find her world's Keyhole.
• The King of Fighters: Because Gaidel refused to take part of Goenitz's plan of resurrecting Orochi, he manipulated Gaidel's daughter Leona into her Riot of the Blood mode and had her slaughter her whole clan.
• In Knights of the Old Republic II: The Sith Lords, the psychotic Wookiee bounty hunter Hanharr is said to have slaughtered his own tribe before being enslaved by the Czerka Corporation, but no one on Nar Shaddaa is sure if this is true. If you recruit Hanharr to your party by being Dark Sided and gain enough influence with him, he reveals that while his tribe exiled him due to his bloodthirsty nature, he knew they'd be enslaved by the Czerka, so he killed them in their sleep to spare them from that fate. He also reveals that he wishes to join his tribe in afterlife and earn their forgiveness.
• The Legend of Zelda: Tears of the Kingdom: After becoming the Demon King, Ganondorf creates a demonic army to destroy Hyrule so he then remake it in his own image. This also includes the Gerudo Desert, the home of his people, the Gerudo. His monstrous actions against the Gerudo prove to be the catalyst for the entire race to turn against their former chieftain, something that Ganondorf didn't forget when he's sealed away for over 10,000 years. After being freed, Ganondorf sends a sandstorm and a Zombie Apocalypse to destroy the present-day Gerudo both as payback for their role in defeating him and to prevent a new Gerudo sage from being chosen.
• The Master Ravager from Minion Masters single-handedly killed every living thing on his home planet.
• In NetHack, the Scroll of Genocide lets you type in the name of any type of creature, and it will kill every one of them. If you type in your own race or class, you've just performed this trope (and killed yourself in the most extreme way possible). You can survive this by using a Wand of Polymorph to turn into a different creature, but you'll just die instantly as soon as you change back.
• Ratchet & Clank Future: Tools of Destruction: Emperor Percival Tachyon is hell-bent on killing off all Lombaxes in existence, including our protagonist, for banishing his Always Chaotic Evil race from the universe — even though he was raised by them from a hatchling despite his evil heritage.
• In Runescape, the War God, Bandos, got his start as a sadistic mortal warlord. He gradually wiped out tribe after tribe. He ultimately killed the god that protected his homeworld from asteroids both to claim the god's power and out of a deliberate desire to wipe out his entire species as a testament to his glory.
• Shantae: Half-Genie Hero: In the bad ending, Shantae is forced to destroy the corrupted genie realm, effectively committing genocide against her own people, to protect the world.
• In Strider 2, Strider Hien betrayed the Strider organization to join Grandmaster Meio, and his actions led to the group's total extermination...the Sole Survivor of which was Hiryu himself, now determined to complete the group's final assignment: hunt Meio down.
• While suffering from a case of Amnesiac Dissonance, Tatsumaru from the second Tenchu game virtually destroys his own clan, leaving only a few survivors, including the two main characters.
• Warframe: The ancient Orokin Empire was brought down by many parties, all of which had good reasons for wanting the Orokin dead, but one of the key players was Ballas, one of the highest-ranking Orokin and the one who created the warframes. He joined with the Sentients and helped them destroy the Orokin from within as revenge for his lover being executed by the Orokin. The worst part of this is that Ballas was on the council that ordered her executed, and voted against her because he couldn't compromise his public persona. He blamed everyone else for this choice.

Visual Novel

• Tsukihime: Arcueid is the last of the vampiric True Ancestors by the misfortune of having slaughtered the hundred or so of her remaining kin in a fit of berserk rage after Michael Roa Valdamjong tricked her into drinking his blood.

Webcomics

• In Drow Tales, Snadhya'rune, the Big Bad, deeply resents her entire family and tricks her clan into infecting themselves with demons so as to eventually ensure their horrific demise.
  • In the Beldrobbaen clan, a traitor suffering from teenage angst and more than a little madness attempts this by infecting her clan with a madness-inducing plague.
• In Freefall, two of the three individuals trying to destroy the half-billion fully sapient robots on the planet Jean are robots themselves. One came to believe that it was necessary for humanity's long-term well-being, regardless of what humans say on the matter; the other is constrained by the third - a Corrupt Corporate Executive literally telling it what to think.
• In Star Power the Countess killed first her mother, and then the rest of her species for what she considered to be cowardice, aka retreating from certain extinction at the hands of the empire they tried to conquer.
• Slightly Damned Mr. Moonshade is a descendant of the Guardian Moku who has murdered both Moku and everyone else descended from Moku, including his own daughter, in order to steal Moku's powers. And he plans to kill any other Guardian and their descendants who interfere Hell's invasion of Medius. So far he has killed the guardian Meli and may have killed others.
• In Homestuck, several examples:
  • Playing Sburb triggers an apocalypse that wipes out all humans in the world except for the players (and a very few close relations).
  • The same is true of Sgrub with the trolls, though due to the next event it sort of doesn't matter.
  • When the Heiress Apparent leaves, her Lusus releases the Vast Glub, which kills all trolls everywhere in the universe except the Empress.
• This is the ultimate goal of OTHAR TRYGGVASEN, Gentleman Adventurer! from Girl Genius. He plans to kill all Sparks (natural-born mad scientists)... himself last. (The idea that new Sparks would keep being born after this was accomplished since Sparks don't always have Sparky parents, seems not to occur to him.)
• Attempted by proxy in 8-Bit Theater: Muffin the Dragon's Evil Plan was to found an order of dragon-hunting knights, use them to kill the other dragons, take their power and wealth, and then slowly destroy the dragon-hunters. The Light Warriors, who encounter several dragons over the course of the story, point out she didn't really do a good job of it.

Western Animation

• In Batman: The Brave and the Bold, the Faceless Hunter reveals that he became Starro's herald in return for Starro destroying his own planet.
• In Beast Machines, Megatron develops a deep hatred for organics, to the point of eliminating any Maximals and Predacons on Cybertron for their Beast Modes. However, he still has his Transmetal II dragon form. He spends the series finding a way to get rid of it so he can achieve absolute "perfection".
• Gravity Falls: Bill Cipher heavily implies he destroyed his original dimension, killing everyone else there in the process. This wasn't exactly his intent, but he found it an acceptable consequence of "liberating" the dimensions (i.e. destroying the laws of physics for his own amusement). The Axolotl states that Bill really does regret this—he'll just never admit to himself that it's his fault.
• The Owl House: While Philip Wittebane isn't a witch himself, he does present himself as one in his guise as Emperor Belos to the inhabitants of the Boiling Isles. He fully intends for every single one of his subjects to die by his hands on the Day of Unity. Additionally, while he was originally a fully human Witch Hunter, centuries of consuming the souls of Palismen have resulted in his body mutating into a rotting, skeletal aberration held together only by magic, ironically resulting in Philip being even more inherently magical in nature than the witches and demons he hopes to eradicate.

Real Life

While Real Life examples of racial self-genocides are scant at best, political, cultural, and religious self-genocides have technically happened if you follow the official United Nations definition of genocide.

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• Back in Ancient Greece, tyrants (who are mostly isolated aristocrats) would often have aristocrats killed (when they weren't exiled) arguing that they were stealing land. One of the most well-known cases is those of Cypselus and his son Periandr. Cypselus was a Bacchiadae (a powerful family from Corinth), but would later end up overthrowing them, killing some of them and expelling others. His son and successor Periandr, according to Herodotus and Aristotle, tried to finish his father's job... By slaughtering every aristocrat, including the Bacchiadae. Though, to be fair to Cypselus, the Bacchiadae tried to kill him when he was a baby (but couldn't bring themselves to do it) due to a prophecy stating that he would later overthrow them. Guess what happened.
• One might see this in the histories of countries that have converted to Christianity or Islam, where followers of the old pagan religions and traditions were forced to either convert or be put to death, having their temples, monuments and written records destroyed, thereby making it a religious and cultural genocide committed by its former adherents. The Roman Empire is possibly the Ur-Example of this: at one point dedicated to the deities of Classical Mythology to the point of persecuting Christians, the Empire eventually converted to Christianity and began persecuting anyone who worshiped the old Roman gods.
• The Purge often takes the form of this. For example, Pol Pot and the Khmer Rouge government killed over a quarter of Cambodia's population, mainly targeting intellectuals and people connected to the old regime but also killing pretty much anyone else they didn't like. As another example, back to Ancient Rome, their military had an official policy called "decimation" that mixed this trope with Shoot Your Mate and used from time to time against military units accused of cowardice, mutiny, or particularly notable failure. The officers would all be executed, but then the enlisted men would draw lots — and the one man in ten who was particularly unlucky would then be beaten to death by the other nine. If the others refused to kill their former compatriot and maybe friend, all ten would be executed. Decimation was designed to make the legions more afraid of the consequences of cowardice or failure in battle than they were of the battle itself.
• The Imperial Chinese warlord Zhang Xianzhong amassed a rebellion to conquer the Sichuan region of China and proceeded to order his soldiers to kill everyone who objected to his rule. Then, kill the inhabitants of the outlying villages. Then kill the wives of officers who had objected to the previous order. Then large groups of random civilians. Finally, he just ordered them to kill each other in front of his throne made of the severed ears and feet of his enemies. To put the effects of Zhang Xionzhong's reign of the Sichuan region into some kind of perspective, one can keep in mind that the last Ming census figure for Sichuan in 1578, more than 60 years before Zhang entered the region, gave a population of 3,102,073. By 1661, 15 years after Zhang's reign, only 16,096 adult males were registered, and Chengdu was said to have become a virtual ghost town frequented by tigers. Zhang also allegedly had a stone inscribed with an explanation of his Omnicidal Maniac tendencies:
  Heaven brings forth innumerable things to nurture man.
  Man has nothing good with which to recompense Heaven.
  Kill. Kill. Kill. Kill. Kill. Kill. Kill.
  • This stone has been found, but the third line actually says "The spirits and gods are knowing, so reflect on this and examine yourselves." Still pretty chilling, though — just like everything else about Zhang Xianzhong's life.
  • The massacre of Sichuan's population is the reason why the province's current population speak a Mandarin dialect (albeit rather different to Beijing Mandarin) instead of a regional language. Before the 17th century, Sichuan was considered a part of Southern China and spoke a unique Chinese language that's just as divergent to Mandarin as Cantonese, Hokkien, and other southern languages are. After the massacre, the region became devoid of people, and soon the Qing repopulated it with immigrants from Northern China, making it a part of the Mandarin cultural sphere.
• In another Ancient Roman example, when The Roman Republic began its conquests, Latin was but one Italic language amongst several. By the first century BCE, all other Italic languages appear to have become extinct (this have appeared to have been mostly assimilation, but it is still the eradication of cultural heritage by a member of the broader group of that heritage).
• During the War in the Vendée part of The French Revolution, the French Republic's troops killed between 20 and 25% of the population of the area (about 170,000 people) when crushing Royalist insurgents. The use of "genocide" about the events is disputed to this day.

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