Cell planned on becoming one of these after the Cell Games. Once he was finished having his fun on Earth, he planned to destroy it, then travel to other planets and repeat the process. But he was killed before he could get started.
Frieza made a business of this, wiping out all life on planets he came across so he could sell them off to the highest bidder. And there's what he did to Planet Vegeta.
Broly blew up a galaxy, and nearly did the same to the universe just for fun.
Majin Buu's fat form had no real aspirations of genocide, only killing because he was told to by Babidi and he didn't know it was wrong. His later forms, however, know full well that they're doing evil, and enjoy it thoroughly:
Super Buu lived for two things: challenging fights, and eating sweets. When told to go kill off some humans so as to give the heroes more time to train, he proceeds to launch a storm of energy blasts at the planet below that seek out and kill every last human not on the Lookout save three (Hercule/Mr. Satan, who wasn't targeted because he befriended Buu, and Tien & Chiaotzu, who were able to dodge the blasts). Even after gaining intelligence by absorbing Piccolo and Gohan, he still goes on a destructive spree of blowing up cities for fun (after eating the entire contents ofevery sweets shop in it first), lamenting that the lack of people means he can't enjoy their screams.
Kid Buu is considerably more unhinged, and is pure evil. A simple-minded being, being an Omnicidal Maniac is all he knows or cares about; he blows up the Earth simply because it is there, obliterates several other planets while searching for Goku & Vegeta, and then, once everyone in the vicinity is dead, he breaks into the Afterlife so he can keep killing.
Fall, the ultimate Big Bad of NORA: The Last Chronicle of Devildom' was revealed to be this in the final battle by almost absorbing all of the life energy of the Demon World and the Human World with the insane amount of power he had absorbed from Nora, Duece and the Dark Leige destroying all "defective" beings along with it. All of this out of rage and betrayal towards the previous Cerberus, Diegree, after he died giving strength to the current Dark Leige without fighting Fall a final time. After his defeat, he repents by giving Nora his power back along with the stolen power of the Dark Leige, nearly making Nora a Person of Mass Destruction
The Millenium's only motive is to cause endless war and destruction For the Evulz, meaning that the war they caused will end if either they get defeated or their opponent, which is humanity as a whole, gets wiped to extinction.
Valgaav, both The Dragon and Big Bad of Slayers TRY wanted the destruction of everything before merging with Darkstar, believing that oblivion was what the world deserved. Afterwards, the knowledge he gained about the nature of the universe drove him to become a Well-Intentioned Extremist merged with Darkstar's godlike power, intending to destroy the entire world and then remake it without strife or conflict.
In the novel canon, all Mazoku are nihilistic Omnicidal Maniacs; in the anime this is most visible with Hellmaster Fibrizo:
Fibrizo: "I want to be destroyed. I want to be destroyed! Destruction? Yes... Destruction is the ultimate wish of any Monster. That's what we were created for. Isn't it? That's what we were created for! [..] But this destruction shall consume all things! It shall consume the entire world! [...] All the world! Let all the world be destroyed with me!"
Subverted with Xelloss, who pays lip-service to the Mazoku "blow up everything" mentality but clearly enjoys life way too much for him to mean any of it. He attempts to excuse his saving the world from Duragnigdu by saying that destroying the world is his job, not Dark Star's. Riiiiight. We believe you.
At that time he wasn't acting for his own benefit, but working as the envoy of the entire Mazoku race, so presumably the surviving Mazoku Lords agreed on his logic there, as well. Plus he was promised that the power released from the killed Dark Star would be granted to the local Dark Lord, Ruby-Eye Shabranigadu. It's left unclear whether that bargain was held or not, but if it was, then Xelloss definitely hastened the homemade Apocalypse by getting rid of the foreign product.
That deal about getting some of Dark Star's energy was never intended to be fulfilled, probably by both sides - nothing shows this more than the fact that Xelloss betrayed the Overworlders shortly after the deal even got mentioned.
Given that most Mazoku fight damn hard to stay alive, it's entirely possible that Fibrizo was simply nuts, and paying lip-service to the cause of universal destruction is the normal attitude of "sane" Mazoku.
Rau Le Creuset of Mobile SuitGundam SEED isn't perhaps the most obvious, as his goals merely encompass the extinction of humanity, Natural and Coordinator alike. However, given the much smaller scale (the action never extends past Mars due to limited space travel), it's quite omnicidal in context. His motivation for this is that he believes that Humans Are Bastards and have only limped along so far as they have because they have never possessed the means to wipe themselves out before now. He honestly believes that the human race as a whole deserves death, not just for his own admittedly sad life but for all the suffering they inflict upon others that he has seen. Given the atrocities committed by both sides in the war, and the genocidal ambitions of so many in the series, it isn't hard to see his point. In the end, Le Creuset winds up one of the more terrifying examples of this character because his motivations are understandable: it is not impossible to see someone actually winding up with his worldview, rather than just wiping everything out because they're a Card-Carrying Villain.
SD Gundam Force gives us the leader of the Dark Axis, General Zeong. His sole motivation is to become powerful enough to fire a beam that would wipe out all dimensions.
Digimon Adventure has Apocalymon. The name says it all. When he was defeated, he tried to unleash a blast that would eradicate the human world and the Digital World.
Digimon Adventure 02:Big Bad (or so we think at the time) Arukenimon's main plan is to destroy the Cosmic Keystones that maintain the barriers between dimensions, which would cause all dimensions to collide, destroying the multiverse. Her intended Dragon refuses to help on the grounds that she's an unworthy mistress, but eventually decides, for his own reasons, to do the same, making him just as much of an Omnicidal Maniac.
Digimon Tamers features a non-Digimon AI that was designed to prevent other programs from exceeding their boundaries ('cause A.I. Is a Crapshoot) by deleting them if they surpassed a certain stage of development. It decides all humans and Digimon meet criteria for deletion. Then it gets reallynasty.
Digimon Savers, aka Digimon Data Squad, has Yggdrasil/King Drasil, the computer that runs the Digital World. When the previous arc's Big Bag's plan backfires and both worlds are going to collide, he decides that the human world must go. When the Digimon fight against him and his minions to protect it, guess what he then decides? He, too, plans on restarting the Digital World after destroying the old one.
The Millennium Earl: "You have only witnessed the opening chapter... the akuma in this world will continue to evolve. Now begins the journey leading up to the true tragic end. I am the Millennium Earl, the maker of the akuma. I shall obliterate your puny "God" and lead the world to its death with my akuma. An exorcist, a soldier of life. You can't save this world no matter how hard you try."
The Eclipse virus in Force turns a large number of its victims into a mix of this and extreme Jerkass for some reason, dying horribly if they either cease killing or don't have some sort of medical care keeping it at bay.
Sailor Moon has several, Queen Metaria the Big Bad of the Classic season, Wiseman/Death Phantom the Big Bad of the R season, the entire Death Busters organization of the S season and Sailor Galaxia of the Stars season. Sailor Galaxia, in particular, is notable for omniciding at least a half-dozen, and probably much more, habitable planets, before coming to Earth - by the Grand Finale she wipes out all life in the Milky Way galaxy in both the manga and the first anime. Chaos, who directly controls her and is hinted (or outright stated in the manga) to be the Ultimate Evil behind the rest of them, is one too.
Manga!Prince Dimande became one of these after he was forced to kill his brother and The Reveal of the Big Bad's true identity, going so far as to steal the Sliver Crystals in order to cause the destruction of reality itself. It took Sailor Pluto's sacrifice to stop him.
Many Pretty CureBig Bads were omnicidal maniacs. The Dark King in the original series and Max Heart started the trend by trying to destroy the Universe because it was in his nature; Lord Akudaikahn in Splash Star was his Expy; Dune in Heartcatch was defined by his hatred of everything.
The Director of Eternal in Yes! Pretty Cure 5 Go!Go! is this for worlds he considered to have no value. If a world has a value, he'll drain them of every of its values, that is, treasures. Once they ran out of it, he'll first turn everything of that world into stone, before blowing them up to kingdom come.
Ah! My Goddess, of all series, had one. The Lord of Terror aka The Ultimate Destruction Program, a bodiless entity whose one goal is to destroy the universe and recreate it in its own twisted image. Given the highly idealistic nature of the series, it failed (though it was a close call) and was Killed Off for Real when it was tricked into possessing a floppy disk which Skuld erased using a magnet.
In Mahou Sensei Negima!, the Mage of Beginnings and his minions, the three incarnations of Averruncus, want to destroy Magicus Mundus (a pocket dimension planet the size of and dimensionally anchored to Mars). It's ultimately subverted, as Mundus Magicus is collapsing on its own, and the Big Bad thinks that the only way to save everyone is to move all the inhabitants into a Lotus-Eater Machine.
Yami Malik of Yu-Gi-Oh! explicitly states in the manga that all he wants is total destruction of everyone and everything.
The Lucifer and Biscuit Hammer has Big Bad The Mage, who is poised to destroy the Earth by hitting it with a giant Biscuit Hammer. His eventual Start of Darkness reveals that he's done this a lot: Being from the future, he has continually travelled backwards in time and destroyed the Earth at every point in time it existed from the point he gained his powers until now. If the protagonists don't stop him he intends to keep on doing this until the Earth no longer exists at any point in time... Simply because he can.
In Noein, Noein's goal is to absorb all possible futures into his own reality, then end the entire universe.
King Zenoheld from Bakugan eventually decided to do this after undergoing a majorVillainous Breakdown, deciding to destroy the entire universe.
Mag Mel entered the picture with this in mind. His ultimate plan is to destroy the Earth in such a way as to set off a chain reaction to destroy the entire universe.
Dewey Novak in Eureka Seven tries to do this by making the Scub Coral exceed to Limit of Questions (the in-universe theory that only a certain amount of intelligent life can exist in a given space, exceeding this limit causes the collapse of the universe)
The second Friend in 20th Century Boys is this. While the first one was comitting genocide with a killer virus for several reasons, he really wanted to be ruler of the world and be worshipped by his circle of "Friends" (all to satisfy his craving for attention and hatred for Kenji). The second one, however, flat out intends to wipe out all of humanity. Despite pretending to be Fukubei (The first one), he really doesn't care one bit about his ideals and doesn't even intend to save those who do support him. He truly wants to destroy the world and his last trap is an Anti-Proton Bomb.
Folken in the movie version of Escaflowne wants to destroy all of Gaea — because he's just so depressed and just wants it all to end, even though he presents himself as a Social Darwinist to his followers.
Monster has a more realistic version of this in Johan Liebert, while his motives are left somewhat vague, his actions certainly suggest that his ultimate goal is the complete destruction of human society by manipulating everyone he comes across into killing themselves or each other.
In Puella Magi Madoka Magica, after several timelines of amplified power, our cute protagonist becomes this in her Witch form, Kriemhild Gretchen. She wants to make everyone happy, but thinks the only way to achieve that is by killing them all.
In Riki Oh, Mukai wants to wipe out the human race because he thinks that is the only way to end their suffering.
Imperiex of the DCU, a hive minded mechanical entity, saw its purpose as being the "hollowing" of the universe, destroying the flawed creation and remaking it in a new Big Bang. Ironically, the flaw it detected in the universe was itself, and a massive cooperative effort managed to throw him into the past where he in fact became the Big Bang in the first place, via a Stable Time Loop, a fact which Imperiex realizes the moment before it dies.
Spider-Man's Arch-Enemy Dr. Octopus became this during the "Ends of the Earth" storyline. Knowing he was dying, his plan was to use powerful satellite weapons to kill 99% percent of the population of the Earth so that the remaining 1% and all of their descendents would remember him forever. He nearly succeeded. However, just as he was about to pull the switch, Spider-Man pointed out a flaw in his plan: the incredible heat caused by the weapons would leave all the survivors brain-dead. This revelation caused Octopus to hesitate long enough for the hero to pummel him into unconsciousness.
While he does not typically fall under this category, The Joker did, in fact, reach this state during the "Emperor Joker" plotline in the Superman comics. In fact, considering that plot and a number of other situations it could be argued that the only things preventing the Joker from permanently attaining this state are a lack of superpowers and his obsession with Batman.
Thanos is the most famous Marvel Comics example. He has a vision of Death as a beautiful woman and in order to win her favor he embarks on a quest to wreak death and destruction. Although he has stated on multiple occasions that the elimination of all life might destroy Death as well as it would eliminate her need to exist, so he would eliminate half of all life, thus ensuring Death still has a steady supply of souls.
In The Thanos Imperative Thanos goes completely insane when he realizes that his Thanatos Gambit to destroy the Cancer Verse also rendered him immortal, meaning he can never be with Death. He makes an earnest effort to wipe out all life in the Marvel-616 Verse and has to be sealed in what's left of the Cancer Verse to stop him from pulling it off.
On a more planetary scale, Onslaught started out as a mutant supremacist of the same stripe as his psychic 'father', Magneto. After seeing the Age of Apocalypse in Bishop's memories, in which mutants really did rule the world and destroyed it, he decided no one was worthy.
Abraxas also hails from the Marvel Universe. The antithesis of Eternity, it exists only to destroy anything and everything in all creation. Keeping it imprisoned is one of the reasons Galactus needs the life energy from devoured worlds. The one time Abraxas did break free it...wasn't pretty.
Annihilus, also from the Marvel Universe, became one of these during the Annihilation. His vast fleets carved a path of devastation across the galaxy, used a large, tick-like weapon called the Harvester of Sorrows to drain entire planets of their energy to feed on, nearly wiped out the Kree and Skrull empires, and (with the help of Thanos and two cosmic superbeings) imprisoned Galactus himself. Why is he an Omnicidal Maniac instead of just another alien conqueror? Annihilus' true motivation for capturing Galactus was to turn him into a bomb. A bomb that would kill everything in the universe except for himself. What's truly scary is that he came damn close to pulling it off too.
Annihilus was always one of these. In fact, he may have the craziest motivation of any character on this page: He has an irrational fear of death, so he got himself the Cosmic Control Rod, which, among its other powers, ensures that he will never age and never get sick. But...he could still die, if someone or something kills him. His solution? Kill every living thing in the multiverse...so they can't kill him first. This was just the first time he was in a position to act on his omnicidal desires on such a large scale. It doesn't work out so well for Annihilus, since the final battle ends with Nova sticking his hand down Annihilus' throat and ripping his guts out.
All of the Elders of the Universe of Marvel Comics came up with a purpose to keep from going mad from their immortality, but one of them, the Obliterator, was clearly insane from the start. After murdering his entire species, he wandered the universe looking for things to kill, using his powerful high-tech weapons to shoot at anything that moved. (Except the other Elders, the only beings who come close to being his allies.) Fortunately for the universe at large, he has no real confirmed super-powers other than the immortality that all the Elders have (possibly making him the least powerful of the group) and is also not very smart.
Amatsu-Mikaboshi from the Chaos WarCrisis Crossover is also this. He existed long before the universe did and, in the Chaos War, wants to return things to that state. Marvel sure is in love with this trope.
Winter of Stormwatch (also from the Wildstorm universe) becomes this after he flew an Alien-infested Skywatch space station into the sun to save the world. Being an energy absorber, Winter became one with the sun. Trapped by eternal agony he lures out The Authority so they can finally put an end to his life; when it's deemed impossible to kill him without destroying the sun and ending the world, he became enraged. Disgusted by humanity's cruelty, he yells "Your world does not deserve to live" and lashes out. He's eventually stopped by using the Carrier's technology to seal baby universes and was condemned to burn for billions of years. Later on he's released by the new Doctor and revived in his previous normal state. In the latest Stormwatch issues it was revealed he still holds some of the sun's power.
"The Man Without Hope"(MWH) from the Wildstorm Universe. He comes from the future and with his superior technology he's a match for The Authority. The future is grim, blank and full of suffering and he wants to prevent it from happening by ending existence all together. Swift receives knowledge from the mythical "gods" about the dark future and how to prevent it. She mentions how the MWH with all his technology couldn't figure out the problem and fix it. The MWH commits suicide when his plan is ruined by The Authority and a new unknown time line is birthed yet he is still convinced that everyone is screwed. The issue ends with the words "beginning of the end" hinting that the MWH was probably talking about human nature being the problem seeing it's the central theme of the graphic novel, "human on the inside".
One of the four possible backstories for The Phantom Stranger given in his issue of "Secret Origins" features a mad scientist from the future who wants to time travel back to the Big Bang and prevent it from effectively occurring. So not only does he want to destroy the universe, he wants to make sure it never even existed in the first place.
The Dark Judges of Judge Dredd have a philosophy that boils down to this. Undead psychopaths devoted to Law, they figure that since only the living commit crimes, life itself should be made a crime that is punishable by death. They slaughtered the entire population of their world, then found themselves stuck, as they hadn't any form of space travel, making them come off more as Kill All Humans in practice.
Ujo Dasa is a dark sorcerer from the Frazettaverse. He planned to free the Oblivion God "Mirahan" by sacrificing a half-breed human/demon and begin the end of everything. When confronted by his former teacher Dreovid, he says it's better to have "cool darkness than searing light". In the end it was revealed that Ujo was the half-breed and son of Mirahan. The Oblivion God swapped his throne of netherhell with Ujo and we watch him rest in peace.
John "Grimjack" Gaunt walks away from Heaven to save his friends. The consequences were that he was denied any afterlife and was doomed to be reborn remembering his memories for all eternity. His soul was bound to the pan dimensional city known as Cynosure. Cynosure was build to harvest the energies of the multiverse to an entombed supreme being called Dis (firstborn of the multiverse) until it was ready to repeat the birthing process in an unending cycle. Grimjack's latest incarnation travels back in time to warn himself of the doom and to break it he has to end the multiverse by destroying Cynosure. Future Grimjack succeeds in manipulating present John in freeing the Supreme being from his sleep. In Grimjack's second incarnation we see the Supreme being walking around in mortal form giving the demons the chance to end his life and let the multiverse die in entropy. They fail. A huge hint that the multiverse might end up destroyed can be seen in Grimjack's supposedly real father, his uncle Jack. He is a Fey and can look into the future. He describes to a young grimjack the complete dissolution of the multiverse, saying there will be "nothing" after that and also that Grimjack's death would be the most interesting of all. We never see if future Grimjack succeeds because the series ended with the death of the second incarnation.
The demons created to build Cynosure prefer entropy. They did not see the point of constant rebirths so they betrayed their maker.
In a very different way, The Candlemaker also qualifies.
Doomsday from the DCU. The name says it all. He's also one of the most primitive examples, he's little more than a frightened but sadistic alien man-child who wants to kill everything that might be a threat to him. And he thinks everything is a threat.
Maelstrom from the Marvel universe. He's the champion of Oblivion and constantly schemes to destroy everything.
Amodeus Q. Termineus from the Marvel universe sought the shattered fragments of the Nexus of all Realities. With them in possession he could destroy the Multiverse.
The Cult of Entropy seeks to speed up the destruction of the Marvel Universe/Multiverse.
The Sonic the Hedgehog comics have Dr. Finitevus, who firmly believes that the world is corrupt and needs to be "purified in emerald fire". That's the reason he manipulated Knuckles into becoming the new Enerjak, knowing that the power would drive him crazy and lead to him going on a rampage. He hasn't tried anything major since, but he's still convinced of the righteousness of his actions and will probably try again.
The only character who manages to be even more omnicidal than Zachary is Sonic's Superpowered Evil Side, Super Sonic, who had no real plan beyond destroying whatever was at hand when Sonic transformed.
After a Villainous Breakdown Dr. Robotnik gives up trying to rule Mobius and tries to destroy it outright.
The light-hearted nature of Captain Marvel can distract you from Sivana being this in one story. Because Captain Marvel prevents his plan to take over the Rock of Eternity so he can take over the Universe, Sivana tries to activate a Proton Bomb to destroy the Rock of Eternity, which is the Keystone of the Universe and will cause its destruction, even killing himself, deciding if he can't rule the Universe he'll wreck it. He is even laughing at this as he wants one last laugh. Just look at his reaction
The Mad Angel Apolyon from the Chaos!Multiverse stole secret knowledge from God and uncovered the truth that nothing really matters. Lucifer fearing this truth imprisoned and tortured Apolyon for a thousand years. After he was released God confided in him that for Heaven to exist, there must be a Hell. Apolyon betrays God and wants to destroy all of creation beginning with Hell. Without its counterpart, Heaven will fall and in turn so will God. In the end as Apolyon said, there will be nothing!
Talita from Terror,Inc was trapped between life and death in a void of blackness for 800 years. She went completely mad and came to love the Void. After she was resurrected she feared her commitment to the Void: "I feel...a strength coursing through me...yes...yes..I worried i might lose faith as the pain left me. I feel joy,strength,lust all raging through me...ALL PALE BEFORE THE EMPTINESS". Before she ends the world she wants to taste life followed by nothing.
The Reverend Jeremiah Hatch from the DCU. A brilliant student but mentally unstable he was dismissed from seminary and flunked out. He went to Vietnam pretending to be a chaplain. The ugliness of the war he witnessed broke him and he started hearing a malicious voice. Jeremiah realized that life is a nightmare from which there is no awakening and he threw away his cross followed by butchering both allies and enemies alike. His new mission is to serve the Almighty by serving his enemy:"To hasten the corruption,to nurture the foulness until the Almighty has no choice but to rain down fire and brimstone and end the ugliness,the pain, the suffering". His corruption of the Mayor of Hub City was to get him into the White House and start a War.
The Ogdru Jahad from Hellboy want to burn the Earth to a cinder
Lucifer: Fenris the Wolf is Destruction personified (and likely an aspect of Destruction of the Endless). His goal is to destroy Creation by attacking the seat of God in Heaven. Lucifer stands in his way.
Fenris is assisted in his endaveour to end all of creation by the gods Abonsam and Bet Jo'gie. Abonsam infused with the essence of Fenris willingly gave his life to perform his greatest trick and ultimately dooming Yggdrasil. Bet fails in her attempt to seduce Charlie and dies by his hands.
The Barrowjane Conspirators to destroy Creation,dethrone God and punish him included Lilith, Sandalphon, The Silk Man and Berim from the Jin En Mok. All had their own reasons for participating: Lilith wanted vengeance against God and Heaven for casting her out of Eden, Sandalphon wins the victory that was denied to Lucifer, The Silk Man wants his own universe and when creation ends the Jin En Mok will finally be reborn as themselves.
Master Darque from the new Valiant Universe. After destroying countless worlds he is coming for Earth. He wants to use the souls in Deadside to break down the barriers between worlds and kill every living being. Using all the souls to become a God: "Every creature on this world raises its head against a background of infinite carnage and smiles at the sun and declares the world good. We are all monsters. Because the Universe we live in is monstrous. But we are blind to it. We do not see the endless horror that underpins our lives. Because God is a sadist. The perversity of this reality is undeniable proof of both his existence and his malice. And it is our duty to become his superior. I will find him. I will challenge him. I will free us. I will make him pay for what he has done. I will break the wheel. I will end all suffering. And you would stop this?". Darque only wants Godhood so he can erase all of existence and bring blessed Oblivion to everything, himself included.
Deadside in the old Valiant Universe was a terrible place where all souls eventually come no matter how they lived be it good or evil.There is no Heaven nor Hell. Billions upon billions of souls trapped for all eternity screaming in madness. In the new Valiant Universe it seems to be toned down a bit but it's still a terrible place where lost souls find no peace. Darque also comments on the nature of souls and its curse: "Even the smallest of them. There is something in all of use that persists beyond death. You would call this a soul. The essence of a thing that is indestructible. Something that survives. Something that fears. Something that suffers. This is cruelty. This is madness. To know that your suffering will never end. Because that is the point of the soul. Suffering without limit. Without Surcease."
Pain, the servant of Desire schemed to end the world/reality/time by manipulating Adam Case. He was not alone as he was backed by a group of mythological powers:
Coatlicue, the Aztec earth mother goddess suffers immensely because of the pollution of the earth. The only way to stop the poison coursing through her veins is to destroy the world and she would gladly give her life for that purpose.
Tezcatlipoca, the Aztec god of night and confusion,betrayal,divination,etc...grew tired of life and decided to team up with Pain to obtain his one way to ticket to that "permanent vacation". He changes his mind at the end of the series when he has found fun in screwing with people on "a personal level". His lover "Leatherette" follows suit and betrays Pain .
Leatherette, a demon who works directly under Pain and shares Tezcatlipoca's reason for ending the world. The two eventually find purpose in raising hell on earth and betray Pain.
Tantalus was cursed by having immense desire and never be able to fulfill it. He was betrayed at the last battle and found momentary peace at the hands of Enna when he shot him up with heroin.
Enna, an old Babylonian Plague God has adapted to the modern times and delivers plagues of pharmecuetical origin like heroin. Only when he has dipped into his own pharmacuetical supply does he refuse to help Pain end time. His new plan is to destroy Pain but is stopped by Desire herself.
Crowned Death's cult revolves around decrying 'the blight that is life' and celebrateing 'the beauty of death, the end of existence'. Mukrezar, upon his resurrection, notes tongue-in-cheek that Crowned Death's followers continue to spread that very message... even after death. Mukrezar himself probably qualifies, though his antics seem to be more motivated by It Amused Me than any desire for destruction itself.
Entropy from the Pony POV Series is one, but an interesting version. She's not actually evil, at least that's not why she does it. She's literally the Anthropomorphic Personification of the end of the universe, and a natural force of the universe. It's pretty much her job to be an Omnicidal Maniac.
We eventually see the rise of another one in the Dark World. Fluttercruel, upon witnessing Rancor betraying Discord—mortally wounding him to steal Destruction's power—suffers a Villainous Breakdown; unwilling to believe her aunt would betray family, she blames everything on the heroes. She then absorbs the Shadows of Existence, turns into a full Draconequus, and says she's going to kill them and everything else until she and her father are all that's left.
As shown in a flashback episode to the Final Battle of the Age of Myths (G1), there was Lilith, the First Witch, a being of such power and pure evil that she could and would have drained the life from the whole world, leaving nothing but dust and living shadows that would exist only to serve her.
Red Cyclone in Ace Combat The Equestrian War sees ponies as weaklings and wouldn't like to think of them as anything other than an extinct race. In chapter 19, he goes as far as trying to detonate a burst missile above Fortress Intimidation, which would inevitably catch other griffins in its explosions. When Zeakros informs him of that, what is his response?
Red Cyclone: Like I care. So what if a few griffins need to be sacrificed? If it will mean the destruction of those pathetic ponies, then I’ll take that chance! Besides, they’re nothing but expendable pawns to me. I can replace them easily.
A Future of Friendship, A History of Hate: Back at the dawn of time, the other Sentiox were sickened by Ruinate intentionally making Equestria a Crapsack World, so took control of it away from him and gave it to his sister Amity. This caused him to destroy several of their worlds to spite them... at which point he discovered he liked destroying worlds. At that point, he decided to destroy everything, which is what eventually led to him being sealed away. Now that he's free, he's planning on picking up where he left off as soon as he's done returning Equestria to the way it was under his initial rule.
Villain: "To unmake a world... the first of many..."
Films — Animated
Implied to be the case with the lich tyrant the Horned King from The Black Cauldron. His goal: raise an undead army to conquer and enslave the world. He sacrifices his living servants to the Cauldron Born and triumphantly boasts that "our" time has finally come when he raises them, meaning he wants to rule as a god-king over the dead.
(Agent) Smith from The Matrix film series, born of his sheer hatred for his existence. The original film reveals that Smith hates the Matrix at least as much as he hates humans, and that he also hates the Matrix just as much as the Redpills hate it, so it is very likely that he had plans during even the original film to eliminate the Matrix, and Neo defeating him only gave him the capability to act upon this desire. In the sequels, Smith, corrupted into a virus after his first fight with Neo, has gone rogue and now considers both the machines and humans as equally flawed and deserving of extinction. Whereas he originally just wanted to destroy Zion, his new goal is to infect and destroy everything, which would also destroy him.
Although the Earth and Federation have faced plenty of Earth Shattering Kabooms through the Star Trek movies, the villain closest to being an Omnicidal Maniac is Nero from the 2009 film: driven insane by grief over the destruction of his homeworld, he has no plans for galactic conquest or delusions of godhood. His only remaining purpose in life is to destroy each and every planet in the Federation.
In Resident Evil: Retribution, it's established that the Red Queen AI has gone completely Ax-Crazy since we last saw her, and has now taken over the Umbrella Corporation, intending to use its resources and the T-Virus created monsters to wipe out all life on Earth. This is enough to even make fellow villain Weskerteam up with Alice and her allies to stop her.
In The Satan Bug, insane millionaire Charles Ainsley makes it very clear to the hero that he's perfectly happy to unleash the title plague and wipe out all life on Earth. He himself has been made immune to the Satan Bug, and would live cheerfully alone on a dead world.
The title villain in Warlock tries to collect the Grand Grimoire to reverse God's work and unmake creation itself to advance himself in Satan's eyes.
In Thor: The Dark World, Malekith wants to destroy all Nine Worlds. He feels that our entire multiverse "should never have existed".
Alfred Pennyworth: Well, because he thought it was good sport. Because some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.
In Peter David's Star Trek novel Q-Squared, Trelane becomes an Omnicidal Maniac who wants to wipe out all of creation but he wants to practice, so he starts by smooshing a "mere" three adjacent universes together into a chaotic orgy of violence and death.
The clone of Victor Helios (Doctor Frankenstein) from Dean KoontzLost Souls wants to feed all humanity to some nanite colonies he created. After all of humanity is dead he will die himself to reverse Genesis.
In the Star Trek: Deep Space Nine trilogy Star Trek: Millennium, the Grigari (who scare the Borg) worship an offshoot of the Pah-Wraiths, who want to reduce the physical universe—including all of history, not just the present—to a timeless, spaceless mathematical abstraction. They succeed.
Michael Swanwick's two parallel novels The Iron Dragon's Daughter and Jack Faust are both devoted to showing how an initially fairly sympathetic character can turn into one of these. In both books, it roughly boils down to living in a Crapsack World and being cruelly manipulated by a covert Evil Mentor.
In Runemarks, the Whisperer seeks to start the End of Everything so that it can create a new world where it is in supreme control of everything, a desire stemming from being used as, essentially, a Magic 8-Ball by the Norse gods.
The eponymous machines of Fred Saberhagen's Berserker series will stop at nothing less than the total eradication of all life. Note that this was what they were programmed to do (though this was supposed to be targeted only at a certain enemy star empire), so they don't exactly fit the mold — but whoever programmed them to do it probably did.
In the Discworld novels, we have the Auditors. They crave an orderly universe, and hence want to extinguish all life because life is unpredictable.
In David Eddings' The Redemption of Althalus, the god of destruction, Daeva, wants to undo all creation. Interestingly, Daeva was originally a good god, or at least neutral, and had the job of destroying things that were no longer necessary so that creation wouldn't become overpopulated. However, only destroying things meant that Daeva felt nothing but emptiness, whereas his brother Deiwos and sister Dweia got to feel the joy and love of creation respectively. Daeva tried to find a friend in Ghend but if anything, Ghend's company was what finally tipped him over the edge into destroying everything so everyone would feel the same nothingness that he feels, as well as breaking the power of Deiwos and Dweia.
Hactar, from Life, the Universe and Everything, is an ancient, sentient computer that was ordered to design the "Ultimate Weapon", and pulverized for disobeying that command (it couldn't conceive of any possible scenario where destroying the universe would be a preferable option). Set adrift as an interstellar cloud of still barely-functioning dust, Hactar spends the next several billion years manipulating another planet's inhabitants into reaching the same xenophobic cultural state as its creators, and then reinventing and triggering the same super-weapon in order to put an end to all of existence. Hactar explains its motives as mostly simply fulfilling its original function, but partly to take revenge on the universe for the eons of suffering it has endured as a result of its original decision.
The Xul from the Heritage/Legacy/Inheritance trilogies by Ian S. Douglas. They wipe out every race that is more advanced than the bronze age because they could be a threat.
Ruin, Big Bad of Brandon Sanderson's Mistborn trilogy. It was one of the two primal gods (its counterpart was Preservation), who combined their powers to create the world- something to which Ruin agreed only on the condition that it would get to destroy said world someday. To be fair, one can't really hold this against Ruin, as it's the literal god of destruction and is just doing its job, but still the thing seems incapable of recognizing that unchecked destruction is bad (or maybe it does recognize it, but because of what it is it is incapable of caring). On the other hand, it's worth noting that he was apparently a human who became Ruin, so....Possibly less force of nature, more psycho who likes to destroy things.
The main villain of The Dark Tower series. The Crimson King wants to undo all of creation and plunge every universe that has ever existed back into a primordial soup of space-time dis-continuum. The reason: that primordial soup, which was pure magical energy, was what the Crimson King lived in before reality came about, and he wants to go back to living in the primordial soup.
The Speaking Gun, from the Nightside series, is an organic sentient weapon that's capable of annihilating all of creation. And boy, oh boy, does it ever want to destroy it all, if only it could pull its own trigger....
Morgoth of The Silmarillion is called "the Dark Enemy of the World" for a reason - his ultimate goal is simply to destroy the Earth, reducing it to the original primordial void. This mad scheme is in contrast to his apprentice Sauron (later the Big Bad of The Lord of the Rings) whose original motivation was to impose order and structure upon what he saw as a chaotic and disordered world.
Though under Morgoth's influence, Sauron was infected with some seeds of the same madness. As JRRT notes at one point, rebellion against the Creator leads naturally toward nihilism. Ironically, Morgoth has a goal that simply can not be achieved, the universe can only be changed, not unmade, by any power less than God. JRRT noted that Morgorth, if he could, would grind the universe to dust, and then hate the dust because it was made by Eru (God), but the dust would still exist, frustrating Morgoth...and the world could in theory by restored by the other Valar.
This idea of leading "naturally toward nihilism" was the root for Morgoth as well. His desire to destroy the world came out of jealousy, because his original desire, before descending into full-blown evil, was to create of his own will, completely independently of the designs of Eru. It was only when he learned that he could not do so (or would not be allowed to do so by his kindred) that he resolved to destroy everything. Similarly Sauron's destructive tendencies came from a need to remove those who would stand in the way of his supposed order-bringing mission.
Chaos from the Dragonlance series of novels wants to destroy Krynn, and probably the rest of the universe as well. Chaos is the wellspring from which everything came, and also from which everything will return, the Aspect of Chaos that emerged in Dragons of Summer Flame just wanted to hasten the process. The deity Morgion also appears to have some Omnicidal Maniac tendencies, as he is the god of Madness and Disease. One of his lines in a novel is I am Morgion...I am the end of all things.
In the second two books of the Old Kingdom trilogy Orannis the Destroyer is released and wants to, well, destroy everything.
Wyrm, the enormous serpent who is the Big Bad of The Book of the Dun Cow, plans to burst out of the Earth and destroy everything in the universe. It is even explicitly stated that he is capable of killing angels if he wants to.
"The Great Lord of the Dark" from the Wheel of Time series: while most of his followers believe that after he his freed and remakes the world they will rule beneath him, a recent book showed that Moridin/Ishmael claims that they are all fools because when The Dark One is freed he will simply destroy everything, including his own worshipers.
Moridin expresses that he's quite alright with this scenario, too, as he is quite sick of the cyclic nature of time. This may qualify as a Suicidal Cosmic Temper Tantrum, seeing as how he'll cease to exist too and is very much aware of this. In fact, it's a good portion of why he keeps working with The Dark One.
The White Witch from The Chronicles of Narnia is pretty nasty, but you don't know how utterly evil she actually is until the prequelThe Magician's Nephew. She used the Deplorable Word to wipe out every single life form in her universe except herself, and then preserved herself until someone could free her. When she left her universe, it apparently vanished from existence, as the last living organism was now gone. The whole thing was less that she wanted to destroy everything and more that she was losing the war against her sister and figured it was the only way to survive.
Vilkas of Tales of Kolmar is a heroic mage with immense power that he never uses more than a trace of. This is because he often has dreams he think will come true - that one day he will have to use his full potential, and at that point it goes one of two ways. Either he will become a Sky God of purest benevolence, helping everyone and guiding the world to an age of utter prosperity, or a demon will attack him and he will kill it with a flick of his power. Then he will become what he calls "The Death Of The World" and kill every living thing on Kolmar and in the Hells, finishing by reaching out and crushing the sun in his hand. Either way it feels fantastic, and he's laughing the whole time. He does have to call on that potential and starts well on his way to being the Death Of The World before someone snaps him out of it. He hates them for that since it means the pure delight of genocide suddenly sours, but gets over it eventually and just becomes a strong but unspectacular healer-mage.
Cronal from Luke Skywalker and the Shadows of Mindor was of an order that maintained that the only real power is destruction, and see the Force as nothing but "the Dark". His plan was to kill everyone and accelerate the heat-death of the universe; then he would have his own permission to die.
In what has got to be the weirdest example of this trope ever, Tobias from Animorphs becomes this in the climax of Megamorphs #02: In the Time of the Dinosaurs. Tobias, just so you know, is firmly one of the heroes. He's The Chosen One. And yet he coldly manipulates his teammates and the resident aliens they're allied with in order to prevent the destruction of a comet set to crash into Earth. Yes, that comet. Which not only wipes out all the dinosaurs, but the entirety of the peaceful Mercora race as well. When confronted, Tobias becomes furious and cites I Did What I Had to Do as the excuse for his genocide. Most disappointingly, the entire sordid incident is never mentioned again, putting Tobias firmly in the rank of Karma Houdini, although the Megamorphs books are hard to tie to/place in the canon timeline.
Of course, if the comet doesn't wipe out the dinosaurs, then the human race can't develop to replace them, which would result in an omnicide-by-retcon of the humans instead, so Tobias would have been an Omnicidal Maniac either way.
The Dune prequel novels establish that Earth has been destroyed, because of the Titans, human brains in warmechs, who now are intent on killing or enslaving all humans in the galaxy. Conversely, after the Titans attack human planets, the Butlerian Jihad begins and the humans order all thinking machines destroyed.
Legacy of the Dragokin: After Daniar points out that women are not morally superior to men, Kthonia decides to kill everyone.
Dark magic caused Shruikan from the Inheritance Cycle to go batshit insane and become like this.
Lord Foulthe Despiser from the Chronicles of Thomas Covenant has the ultimate goal of destroying the Arch of Time, which would unmake physical reality in the process- because he's actually a prisoner in physical reality, and wants to leave. Being exactly who and what he is, even if he didn't want to escape from the world he'd probably still try to destroy it (after a few millennia of torturing everyone) For the Evulz.
Nick Perumov's Keeper of the Swords series is, in fact, a Thirty Omnicidal Maniac Pileup. We have no less than three main ones: The Unnameable One, a bog-standard Eldritch Abomination made of existential nothing, and his minions the Western Darkness and the Goatlegs; the Savior, an evil Crystal Dragon Jesus who wants to have a biblical Apocalypse; the Faraways, mysterious entities who want to create a new big-G God and do not care about the effects of this on the multiverse. In addition to this, the shenanigans of various normally non-omnicidal multiversal entities like the Fallen Gods often result in destruction of a dimension or two, in which case the lack of true omnicidalness of those entities is little comfort for those living in a world doomed by them; the series is set in only two worlds, which is small spare change for those entities. Have we mentioned that those two worlds are in the focus of attention of the big three Omnicidal Maniacs?
In Angel, there's The Senior Partners of Wolfram and Hart. While the Partners have grown powerful by feeding on humanity's potential for evil, they ultimately want to bring about the Apocalypse. They keep Angel around because he is destined to play a part in it, and they want to make sure it's on the side of evil.
The Thirdspace Aliens from Babylon 5, evil, psychotic, telepathic creatures powerful enough to frighten the damn Vorlons, are described as "anti-life itself" bent on destroying everything in both their universe AND our universe.
Shadows seem like this at first but the reality turns to be a bit murkier.
Glory doesn't seem to care that the activation of the Key will irreversibly fuck up everything, possibly because she can survive (or thinks she can survive) the chaos that would descend upon all universes. Being a Hell God of primordial chaos who was so powerful, evil, and destructive that her peers in the Hell God business pulled an Enemy Mine to depose her probably helps too.
Doctor Who has plenty of these, with the trope perfected in Sutekh from "Pyramids of Mars", who wants to destroy all life in the universe.
Sutekh: I am Sutekh the Destroyer. Where I tread, I leave nothing but dust and darkness. I find that good.
The Doctor Who New Series "perfected trope" can be found in Fourth Season episode "Journey's End", where Old Series villain Davros has taken Dalek xenophobia to its extreme by creating a "Reality Bomb" which will annihilate reality.
In the old series, Davros never quite attempted this, but conversations between him and the Doctor suggested he would if he had the power - simply because he could. Which pretty much sums up why he'd want to destroy all of reality in Series 4 - because he can. Should be noted that though he will survive along with the Daleks, he takes it for granted that they eventually will kill him too once the bomb has done its job.
More than just suggested; in the episode where Davros was introduced, the Doctor asked him, "If you created a virus that, if released, would destroy all other life in the universe, would you release it?" After talking a bit about the incredible power he would hold, Davros concluded that if he created such a virus, yes, he would release it, simply because he could.
Fenric, though he didn't get as close, also counts.
Or Light - the alien researcher who decided to wipe out all life on Earth because he couldn't tolerate how everything was constantly evolving.
Or the Daleks, Davros' omnicidal mutant creations and the Doctor's collective archenemy. Their entire purpose of being is to eliminate everything in the universe, and on occasion the multiverse, that is "non-Dalek" on the basis of their own supposed genetic superiority. Davros learnt the hard way that this logically includes him as well.
The Bio-Vizier Mantrid in Lexx went from a garden-variety psychopath to a complete nihilist who managed to destroy the 'Light' Universe with his Drone Arms, which would obliterate a planet and use the materials to make new Drone Arms. They were capable of moving faster than light (considerably so), and he was eventually tricked (AFTER they had consumed the 'Light' universe) into bringing them too close together, where their collective gravity ended up collapsing into a 'Big Crunch', the opposite of a Big Bang. The so-called "Heroes" were shunted into the 'Dark' universe by the forces of the collapse.
Early Power Rangers villains were always talking about conquering or destroying the world, the same villain going from one to the other and back frequently. From season five onward, villains are more certain about what it is they're after.
Anubis in Stargate SG-1. While most Goa'uld we meet are Evil Overlords, this guy stands out. The blatantly evil race whose hat is "Evil Overlord with a god complex" decided this guy was too dangerous because unlike your average Goa'uld, he doesn't want to conquer the entire galaxy, he wants to wipe out all life in it. And then repopulate it with lifeforms of his design, but that's an academic distinction to anyone that's not Anubis.
In the Star Trek: Millennium novels, Weyoun becomes host to a Pah-Wraith after the creation of the red wormhole. The Pah-Wraiths' eventual goal is to have the blue and the red wormholes open in immediate proximity to one another, resulting in an epic battle between the Prophets and the Pah-Wraiths. However, the merging of the wormholes will result in a Warp 10 shockwave that will obliterate everything in its path. Given that Warp 10 means "simultaneously everywhere in the universe", the shockwave will result in the end of everything. Luckily, the Prophets win the battle and restore everything to the way it was.
In one James Bond inspired holo suite episode, the Big Bad's plan was to cause gigantic earthquakes at certain points along the globe, killing almost everyone except a select few he has decided to save, to rebuild humanity.
From the original series, there's Matter!Lazarus from "The Alternative Factor". In order to kill his enemy, his Anti-Matter double, he has to cross the threshold into the other universe, but bumping into said enemy while in the same universe will destroy both universes. Despite knowing this, he's so far gone that he simply doesn't care.
Azkadellia from Tin Man creates a device which the Mystic Man states will bring about "the complete destruction of the OZ." The device is designed to fix the two suns of the OZ in a permanent solar eclipse, which as any scientist will tell you, will ultimately result in the destruction of all life. There is an extremely rare double-eclipse happening (i.e. both suns "hiding" behind the moon), which Azkadellia plans to lock into place.
H.G. Wells from Warehouse13 uncovers the Minoan Trident, the worlds first weapon of mass destruction, and uses it in a plot to begin a second ice age upon her debronzing. Wells' end of the world plot stemmed from a self realization that present society had not changed for the better since her last appearance in the Victorian era. The trident would have enforced an ice age and therefore caused the world to reset and heal itself of humanity's failure.
GWAR: Several of their songs come back to this theme, most notably Biledriver (Refrain: "I Want to Murder everyone in the entire world..."), Bring Back the Bomb ("I must use the nukes, I can't kill you all with my hands!"), Storm is Coming ("We'll kill EVERY species, not just one or two"), War Is All We Know ("Hatred of all things alive!..."), and We Kill Everything ("And we'll kill everything, including ourselves...")
Mythology and Religion
Egyptian Mythology had two examples. One was Sekhmet, a Blood Knight who may be Hathor'sSuperpowered Evil Side, known to regard everything as an enemy; however, get her drunk and she'll fall asleep and hopefully turn back into Hathor (Ra once did that by dying some beer blood-red). The other was Big Bad Apep/Apophis, the Anthropomorphic Personification of chaos, darkness and all the world's ills. Prior to the demonisation of Set/Sutekh, this was theGod of Evil, who constantly tried to devour Ra (aka the sun), which would end the world. To give you an idea, even after his demonization, it was commonly believed that Set/Sutekh had a role in fighting Apep, as well as having power over storms, and so people prayed to him to fight Apep well and to maybe not hit them with so hard of a storm next time. People always prayed against Apep.
Norse Mythology has most of the frost giants, as well as Jormungandr and Fenrir head in this direction during Ragnarok. Skoll and Hati, the wolves who seek to devour the sun and the moon are also examples. The two worst however, are Surtr, King of the Fire Giants and Lord of Muspelheim, and Nidhoggr. Surtr will lead the sons of Muspel against the Aesir at Ragnarok, slay Frey (who by this point is one of the few gods still standing), slaughter the remaining Aesir, and then set the world itself ablaze. Nidhoggr, in the meantime, is a massive and utterly evil dragon who sits at the roots of Yggdrasil and tries to bring the entirety of creation down into oblivion. It will finally succeed during Ragnarok and, what's worse, survive the end of the world.
The Nuckelavee of Orcadian (from the Orkney Islands north of Scotland) mythology is a truly monstrous example of The Fair Folk. Resembling a skinless rider fused to the back of his monstrous horse, it rises from the sea to spread disease among crops, livestock and people.
In Magic: the Gathering, the Eldrazi are a race of three (known) titanic beings who are born of the Multiverse, who feed off of entire planes of existence. Currently trapped on the plane of Zendikar, they are known to cause swaths of destruction miles wide wherever they roam.
The Excrucians in Nobilis, for reasons best known to themselves.
This was elaborated on in third edition. Deceivers love the world, but they believe that most of the things of the world are lies put between themselves and the thing they love - as Chibi-Ex put it, "all just an illusion, that running and breathing and hoping and living and dying" - and so they try to unmake the lies of the Imperators to free everything. Warmains want to test the world and only extract into the Lands Beyond those things that pass their test (as a result, it is often wise to deliberately throw a contest with a Warmain, since they only try to kill you if you pass). Mimics twist the world rather than destroy it, because by their very nature they are broken, stitched together from fallen Imperators. The truest example of this trope are the Strategists, who hate the world as a crime against the void and have free access to the World-Breaker's Hand, a Gift that can destroy anything.
The Deathlords and their servants, the Abyssal Exalted, from Exalted fit this trope to a T. The Deathlords seek revenge on a world that betrayed them by feeding it to Oblivion, and many of the Abyssals believe that they're delivering the blessed perfection of the grave to a suffering world. This has been backed up mechanically by Second Edition rules; every Abyssal Charm (magic power) is rooted at destroying something, be it a life or a loyalty.
The Neverborn are the ghosts of fundamental entities who cannot be separated from existence, whose death messed up the cycle of reincarnation and created the Underworld and who want to destroy the universe, apparently so that they can finally finish dying.
Large factions of The Fair Folk want to destroy the universe, either because the mere existence of a world with rules and logic and limits disgusts them, or because it is dramatically appropriate for a scary monster and they like looking like scary monsters (or rapturously beautiful Whore-Madonnas or both).
Adorjan murders everything she touches, and would cheerfully kill everyone in existence if she had the chance. Oddly enough, thanks to huge amounts of Blue and Orange Morality, she's actually one of the more compassionate Yozis, although given the nature of her kindness most of her victims would probably be happier if she wasn't.
The demons of the Abyss from the Dungeons & Dragons settings. They are believed to be the will of the Abyss itself, which is endless raw chaos, distilled into sentient and individual form, with the ultimate goal of eradicating everything other than themselves. Assuming they succeed, as Chaotic Evil they'll then turn on each other, and when they are all destroyed, the multiverse will be silent once again. The exception is Graz'zt, who as befitting the Dark Prince of Deception, prefers that the world remain around for him to rule.
While in 3rd and earlier editions this might be an example of Chaotic Stupid, in 4th it's their defining characteristic.
And then there's Tharizdun from the Greyhawk setting whose goal is the destruction of all existence finishing with himself. It took the combined efforts of all the other gods, good and evil, just to imprison him. His credentials grew in 4th Edition, where he actually created the Abyss by throwing a shard of pure Black Magic into the Elemental Chaos.
Thanatos, supreme Immortal of Entropy, supposedly has similar plans for the Mystara cosmology, although given his egotism and cowardice, it's questionable whether he'd ultimately include himself on the To-Be-Annihilated list.
The book Elder Evils is full of Eldritch Abominations who would very much like to destroy the world/worlds/universe/multiverse. In fact, the book suggests that the terms "Elder Evil" and "Omnicidal Maniac" are more-or-less synonymous with each other. Most - but not all - mortal beings that serve these entities qualify as well.
Demons are played differently in Pathfinder—while they love wanton murder and destruction, they don't want to destroy everything because then they'd have no more fun. Instead, the cessation of all life is the goal of the Neutral Evil daemons, who know nothing but hatred for everything, themselves included, and derive pleasure from nothing. To compare the two, whereas a demon would rape you to death for its own enjoyment, a daemon would quickly and efficiently kill you just to snuff you out.
The Asuras are a minor type of Lawful Evil fiends who want to destroy all of divine creation as they are "errors" of the gods, while the Qlippoth want to eradicate all sentient live so no sinful souls arrive in the Abyss to form Demons, so the Qlippoth can reclaim it for them again.
Then there is Rovagug, who is very similar to Tharizdun above, but imprisoned in the core of Golarion (the setting's main planet) instead of outside the universe and is still capable of releasing devasting monsters known as Spawns of Rovagug, the most well known being the Tarrasque.
In the New World of Darkness, while many beings are malevolent and highly destructive, the most noteworthy are from Mage: The Awakening: the Scelesti (mages who serve the abhorrent Abyss, and seek to allow its anti-reality to seep into this world in order to bring it to an end) and the Cult of the Doomsday Clock (a group of mages who believe that the best way to free the souls of humanity is to destroy all of time and history, using their evil clocks, and by becoming living time paradoxes. They also (unknowingly) serve the Abyss).
From the old WoD, there's the Wyrm, the cosmic principle of Destruction, which has found itself trapped in the web of reality, and seeks to destroy everything so it will be free. Also the Underworld's Spectres, who want to drag everything down with them into Oblivion. And the Mages have the Nephandi, who also want to destroy our world, either for its own sake or so that creatures from beyond can replace it.
One Paranoia mission involves a NPC who's decided that everyone else is a traitor (okay, he's right about this part) and needs to be killed, to the point that he would consider destroying all of Alpha Complex (minus him and a hundred-odd loyalists in a bunker) a viable option. And another group of NPCs who would also destroy all of Alpha Complex in order to take out The Computer. Naturally, the PCs encounter an Old Reckoning bomb capable of doing exactly that, and have to figure out a way to keep it away from both groups.
Mr. LeThuy from Over the Edge. He's a nihilist secretly amassing a cult using his charisma. Over time, the members turn into perfect clones of Mr. LeThuy, body, mind and soul. They want a universe where everyone is either dead or another clone, at which point they will destroy the universe.
In the third edition of Warhammer 40,000, the Necrons were driven by an insatiable need to destroy everything alive and/or sentient (it was an academic difference since nobody could ask them which of the two it was), rendering the universe quiet and uninhabited except for themselves. Later this became a tactic to defeat their main enemies, the Warp gods- killing all life would starve off the Warp (the sum total of all emotions). As of their latest codex this has shifted into turning them into Tomb KingsIN SPACE!, making them no longer an example.
Necron Pariah: There is an alternative (to life). There exists a state in which all conflict is resolved and all is cold and silent. There are no wants, no wars, no squabbles. You may call this state death if you wish, but that is a misnomer. Death is but the ending of life, and that is only a means to an end. That end is purity, the time when all is still and unchanging.
The Chaos faction known as the Purge believe the only way to save the galaxy is to kill everything in it. They believe themselves to still be pure; their victims would disagree if they were in any state to do so.
Likewise, the Chaos faction known as the Crimson Slaughter embark on massive killing sprees for the sheer sake of carnage, because these Renegade Space Marines are afflicted by a curse that causes them to be haunted by the ghosts of their victims. Only slaying fresh victims can quiet the voices that will otherwise drive them insane; the bloodier the massacre, the longer the reprieve they get before the voices come back.
This is the true nature of the Army of the Expeditionary Force, from the aptly named 3:16 Carnage Amongst the Stars.
In Warhammer this is the goal of Nagash the Great Necromancer. He wants to kill everyone and raise them as his undead servants.
Vlad von Carstein has a similar goal, but in his case it's more of a Knight Templar thing- the undead are immune to Chaos, so by killing every living thing in existence and reanimating them in his thrall, he's actually saving them from Chaos! .. Or so he says.
The Mexico City Zonemind in GURPS Reign Of Steel take the standard Kill All Humans tendency of the Zoneminds who rule the Earth to the extreme of wanting to eradicate all organic life. It keeps the fact that it is developing plans to do so on a global scale (and not just within its Zone) secret, as several of the other Zoneminds aren't so extreme (or at least are extreme in other ways, like Berlin's irrational obsession with humanity as a threat to nature) and would oppose it by force if they knew about it.
Minecraft brings us the Wither, which is essentially the ultimate griefer. It blows up everything in its path, and holds the philosophy that if something is alive, it must cease to be as such. It's also very good at this too. In-game griefers can be this as well, reducing server populations on death-ban servers to ridiculously low numbers.
Half-Minute Hero has a game mode called hero 30 that reduces this type of villain to a Monster of the Week and uses them as the boss of every single level all of them seeking the destruction of the planet, for reasons that vary from genuine nihilism, to a Giant Enemy Crab upset about not being able walk forwards.
BlazBlue gives us Hazama. He despises any lies hat someone tells him, and what does he call the world? Lies! Lies! Lies!Considering his actions andlack of motives for said actions, the player can tell he's a psychopath that really does want to destroy everything.Although his true goal is to get back at the Master unit and the Real Big Bad Izanami even more so since she wants to create a world of death.
Tales of Graces sees Lambda attempt to invoke this because Humans Are Bastards. What he doesn't count on, however, is Asbel being smarter than he looks. Asbel deconstructs the cliche by pointing out how the destruction of all life accomplishes nothing, doesn't solve any of the issues that people have and doesn't even benefit the one who enacts it in any way (as they will be the only being left alive... and not all the time). This complete obliteration of Lambda's goal is what inspires him to accept Asbel's offer of letting the world live and allowing Asbel to show him that Humans Are Special.
Armored Core: for Answer has Old King. And you when siding with him.
The main villains of Bayonetta are this, as they all want to resurrect Jubileus, who wants to end the current state of existence.
Ancient Domains of Mystery: The goal of the Chaos beings, who invade the realm from another dimension. Also, it is possible for the player to defeat the Chaos God, take his place, and do it by himself.
In The Legend of Zelda Oracle games, Ganon was resurrected into this instead of his usual intelligent self due to an improper sacrifice of his evil surrogate mothers.
Endless Legend has the Cult of The Eternal end, an entire civilization of Omnicidal Maniacs.
Neverwinter Nights 2: The King of Shadows. He was initially created by an ancient empire to protect it from evil forces. There are a series of flukes that turns him evil after the people that made him died off. With nothing left to protect, The King of Shadows goes berserk and decides that the entirety of the Forgotten Realms is responsible for the empire's collapse. He naturally comes to the conclusion that the whole world needs to be destroyed in retaliation.
Akachi the Betrayer in the expansion was cursed by the now-dead god of death, Myrkul. A Horror Hunger has consumed him, leaving him an empty shell with an insatiable need to devour the spirits around him. If left unchecked the curse could devour planes. This is the evil ending of the game. The Player Character can do exactly that, utterly annihilating several gods in an epic battle. It is an example of just how powerful the Spirit-Eater curse is.
Chaos, who came into existence thanks to the Fiends, who were already destroying the world to begin with.
Xande is pissed about being made mortal and wants to put everything into suspended animation, forever. Cloud of Darkness, a personification of the Void wants to reduce everything in both worlds to nothingness.
Zemus wants to exterminate all human life on Earth so that he (and the other Lunarians, maybe) can rule. Zeromus is just evil. Or something.
Exdeath is an arbormorphic personification of evil. Neo Exdeath, a personification of the Void wants to reduce everything (including itself) to nothing... wait...
This was touched upon (vaguely) in Dissidia: Final Fantasy. Cloud of Darkness's "Void" is the destruction of everything, leaving nothing. Exdeath's "Void" is the return of everything to its original state, the realm of the Void. Cloud = Empty universes (AH Class X5), Exdeath = No universes (AH Class Z).
Kefka, who is already quite insane but just got worse due to his acquired power from the Statues, and when the Heroes reveal that despite the fact that he has caused The End of the World as We Know It, they still harbour hopes for the future, he decides to destroy reality and "create a monument to nonexistence."
His pre-fight quote against Exdeath in Dissidia: "Destruction without death? BORING!"
Final Fantasy VII has one, and surprisingly, its not the Big Bad Sephiroth, but rather, his father, Professor Hojo. Aside from the fact that he was the one who created Sephiroth in the first place (both naturally, and artifically, due to being his birth father and injecting him with Jenova's cells while he was still a fetus, respectively), he also was heavily implied, if not outright stated, to have manipulated Sephiroth into doing this course of action, both before and during the events of the game, and if the novellas are anything to go by, he even possessed Sephiroth afterwards, all for the sake of seeing his research prove successful, which is implied to be the total destruction of the planet, or at least severely damage it. It's not even the last time he attempts to do this, either, as Dirge of Cerberus revealed that he also ended up possessing Weiss the Immaculate's body with the intention of tricking the Omega WEAPON, a WEAPON that activates when the end of the world arrives and leaves the planet, into awakening, and it is heavily implied that destroying the world was indeed his intention that time as well.
Ultimecia wants to compress time into a Timey-Wimey Ball so she can recreate the entire universe because she's pissed off about centuries of oppression against her kind. Even though she has a Freudian Excuse it is hardly valid, since these centuries of oppression were really set off when she went back to the time of the story, and pissed everyone off.
Kuja doesn't like the idea of the universe outliving him.
Seymour thinks that life is nothing but suffering, and that the only way of escaping Sin, the cause of it is that everyone should die.
Kam'lanaut and Eald'narche trying to "Open the Gates to Paradise". Which would just have the side effect of killing every non-avatar and non-Zilart on Vana'diel. Promathia wants to release the Emptiness on Vana'diel killing everything so he can finally die.
Galeth wants to destroy all life on Cocoon and Orphan, the fal'Cie who rules over it. Orphan himself just wants to destroy everything.
Caius wants to destroy Etro, the goddess of time and death, in order to save Yeul from a Vicious Cycle of early death and reincarnation. Problem is, Etro's death will cause a Time Crash in which a wave of primordial chaos washes over the world and eventually reduces it (and all of its inhabitants) to nothingness. Caius thinks that this is an acceptable sacrifice to make.
Chaos (again) chooses to destroy the world and himself, after finding that a world without Cosmos was a much emptier existence than he thought it would be.
Dissidia actually has the "take over the world" villains conspiring against the "destroy the world" villains on their team.
Another Square Enix example: the Big Bad of the first Kingdom Hearts game wants The Heartless to destroy everything, since he believes darkness is the natural state of things. He first tries to accomplish this by gathering the seven Princesses and opening the Final Keyhole, and then by opening the Door to Darkness and unleashing hordes of them.
Utsuho Reiuji from Touhou became one after gaining her powers (whether this is because she was tricked into godmodding or simply curious of what god-flesh tastes like is up for discussion). Thankfully, the heroines were able to confront her before she had a strong handle of her new powers.
Id from Xenogears wants to kill everyone and everything, for rather vague reasons. Granted, he IS the embodiment of all hatred and suffering that Fei had mentally suppressed, but it doesn't change the fact that he finds little reason behind his slaughter other than it being fun.
The Burning Legion in the Warcraft games has, as its goal, nothing less than the complete eradication of all life in the universe — and, according to the Back Story, has already destroyed several thousand planets by the time it reaches Azeroth.
Occasionally overlapping with the Burning Legion are the Voidwalkers, who are creatures of pure entropy who exist only to devour the physical world. One of their leaders, Dimensius, is responsible for destroying the Ethereals' homeworld. Players naturally get to punch him out.
Apparently the Twilight's Hammer cult is composed entirely of such maniacs. The ultimate goal of the cult is to bring about the end of Azeroth by any means necessary.
In World of Warcraft's third expansion pack, the Big Bad, Deathwing, is an example of this. When fighting him he has an attack called cataclysm which is meant to completely destroy all life on Azeroth. If he succeeds via this attack or some other, as is shown in the End Time, He would have then killed himself to extinguish all life in the world. His minion/son, Ultraxion, also has an ability, Hour of Twilight, that kills the dragon aspects and allows Deathwing to take over the world (and proceed to extinguish all life).
The Time Devourer from Chrono Cross is apparently Lavos (or one of his spawn) after being removed from time and getting pissed about how unfair life is. After all, he was just doing what he was meant to do. What right do cattle have to persecute or kill the farmer? So it's now going to eat all of time.
Marduk the plane-consuming demon from Sacrifice, whose mere presence on a plane of existence leads to its eventual decay and, ultimately, its complete destruction.
Dimentio, at least to a very narrowly smaller degree, qualifes as well, as he wanted to usurp Bleck and take the Chaos Heart to destroy most of the universe and then remake it. However, he then decides to go back to destroying existence after he was vanquished, even going as far as to leave a shadow of his power behind with the Chaos Heart so that it can last long enough to destroy everything.
The Shivans from the Descent: Freespace series are a race of Omnicidal Maniacs. They've managed to destroy The Ancients, a civilization that was way bigger and more advanced than the Terran and Vasudan races combined. In fact, they've been named after Shiva, "The Destroyer", because they never attempted to communicate and only seems to be interested in blowing up stuff that isn't Shivan. The first game had cutscenes which chronicle the rise and fall of the Ancients from the Ancients' perspective (complete with Ominous Latin Chanting), and they call them "The Destroyers". The cutscenes reveal that the Ancients figured out a way to defeat the Shivan menace, but it was too late. This Ancient information was later discovered by Vasudan scientists giving the Terrans and Vasudans just enough time to save their collective arses. But not before the Vasudan homeworld was completely leveled, killing four billion of them, and just right before the Shivans got to Earth. That's right, not one but TWO (!!) of the most advanced, space-faring races this side of the galaxy would have been wiped out by the Shivans, if it weren't for artifacts left from a very advanced civilization that they did wipe out.
Thirty-two years later in Freespace 2, the Shivans even manage to cause a star to supernova, in a system with billions of civilians in it. Granted, that time around killing non-Shivan stuff didn't seem to be their primary objective. They just killed everyone who got in their way. Even their own ships that seem to have suffered engine failure after emitting the triggering energy pulse and all those ships still in battle with the GTVA. And to heck with collateral damage from the supernova.
In both games, there are speculations from all sides as to why the Shivans seem so bent on killing everyone. The Ancients thought they deserved their fate, for subduing "lesser" civilizations in their conquest of the galaxy. A Terran voice at the end of the first game mentions Shivans as a protector, sort of immune system of the galaxy, wiping out any civilizations that discover subspace to prevent them from being a threat to the younger, less advanced ones. The rogue Admiral Bosch from Freespace 2 thinks humanity has no future with the Vasudans, we're talking about an alliance with the Shivans, man! Admiral Petrarch, your FS2 boss, thinks Shivans are like the Terrans, wandering the galaxy for a way back home (the subspace link to Earth was cut off when the SD Lucifer blew up in subspace in the first game). Nobody really knows though, and the Shivans are unique in that they're a mystery race that actually becomes more mysterious as the series progressed. Nobody will ever know, either, as the original publisher is bankrupt.
There's also Revya him/herself in the Demon Path, who ends up unmaking existence in the 'bad' ending.
Star Control 2: "We are the Ur-Quan Kohr-Ah. We cleanse our destiny. You will soon die. Make whatever rituals are necessary for your species."
The Kohr-Ah are an interesting take on the concept: they do not, believe it or not, hate other species, no do they find other species disgusting. No, their whole motivation for being Omnicidal Maniacs is they're terrified of other species... or, more specifically, terrified of another species growing powerful enough to enslave them. This stems from the horrific mind-controlled enslavement their race suffered at the hands of the Dnyarri. They see wiping out all other forms of life as the safest way to ensure this never happens again. Indeed, if you can get them to talk to you for a while instead of attacking, they're remarkably pleasant and polite... as pleasant a conversationalist as a giant black centipede in a death-dealing war machine can be, anyway.
Prince Luca Blight from Suikoden II is a combination of this trope and Ax-Crazy. He's not a very pleasant guy...
Dorian General Grants, the Big Bad of Tales of the Abyss, sought to annihilate the entire surface of the planet the game's set in, down to the last molecule, and build a new world upon it from scratch.
After Galcian dies in Skies of Arcadia, Ramirez goes insane and shoots for the destruction of the entire world, stating that it is no longer worthy of living. He even gives up his life to fuse with the Ancient Superweapon for Unlimited Power to destroy. In doing so, he mirrors the words of the Silvite Elders, who had the same goal but lacked the means.
Mortimer McMire from the Commander Keen games. In the first game trilogy he attempts to destroy Earth because he considers the human race Too Dumb to Live. After that fails he decides to blow up the whole galaxy instead. And then it turns out that the galaxy destroying scheme was there to distract the hero, and his true goal is nothing less than the destruction of the entire universe! Sadly the next game was never made.
The Void from the EverQuest universe and Big Bad of EverQuest II are a whole dimension's worth of these, by virtue of being the anthropomorphic embodiment of nothingness from before the dawn of creation. They are credited with the destruction of at least five other worlds prior to targeting Norrath and one alternate future shown in the bad ending of a mini-game scenario shows that they are more than capable of wiping Norrath from existence too should its denizens falter in their defense.
Turns out the prophets knew the halo array's true purpose; though whether they accepted the truth (Mercy), denied it (Regret), or used it to their own purposes (Truth) varied from prophet from prophet, and it's still debated among the portion of the fanbase that reads the books.
As a follower of the Mantle, the Ur-Didact originally held fast to the belief that, as a Forerunner (and a Warrior-Servant), he should protect both other species and his own, while having proper respect and admiration for worthy examples of the former (such as humanity). After a rather unhealthy conversation with a Gravemind (i.e. one of his "gods"), he developed a different stance; if it's capable of threatening the Forerunners in any way, it's got to go. This includes humanity and presumably Elites, Brutes, and Prophets as well. Luckily, he took two shots to the chest and was locked in a Cryptum before he could put his plan into action. Unluckily, he was accidentally allowed to escape 100,000 years later, and while his plan to enslave humanity as an AI army was thwarted, he is likely still loose somewhere in the galaxy.
And while we're on the subject of Pokémon, Lysandre in X and Y. His plan is to ensure enough resources for all people on Earth...by killing all Pokemon and most humans.
The planet Meteo from Meteos is a gargantuan malevolent eye that wants to destroy everything in the universe via the endless hordes of meteors he spawns.
In House of the Dead, final boss Magician's first words are "Who are you? Nobody gives me instructions. I shall destroy everything." In House of the Dead 3, final boss Wheel of Fate opens the fight with "I will destroy everything. And resurrect everything." They sound the same for good reason, as the Wheel of Fate is none other than Dr. Curien, Magician's creator.
Lord Ghadius of Klonoa: Door to Phantomile. His quote on the quote page is rather chilling.
The long-term plan of the Thalmor is to erase Talos, then the idea of Men, then the Mundus itself from existence in some plot to return to pre-creation "divinity".
Porky in Mother 3. He wants to destroy the entire world, because he's gone even more insane as a result of the Time Abyss he went through, and that still nobody loves him. Slightly different from the usual in that the world HAS already been destroyed - perhaps even by Porky - and that these people are the last remaining survivors.
Requiem from City of Heroes plans to turn Earth into a homeworld for the Nictus. While that may not be enough to qualify him as an Omnicidal Maniac, you discover an alternate dimension where Requiem's plans have succeeded, and he's gone insane from being the only human left and is trying to destroy the entire multiverse.
You know you're living in what amounts to a crapsack universe when these are the kinds of guys in charge. Such is the cosmos in Lunar Knights, with the Immortals running around with their Planet Eaters, taking over all sorts of worlds and/or destroying them to impose eternity upon the universe. Granted, Lucian and Aaron make life much easier for their world by completely erasing Polidori (he's an Immortal, in case you lost track), but if what Dumas said has any weight to it, there are going to be a lot more on their way...
From Persona 3, both Shuji Ikutsuki and Takaya express an interest in destroying all life. The former seems to be under the impression that he will be spared and given the chance to remake the world in his image after Nyx destroys it, while the latter is already dying and just wants to see everything else go first.
Zone of the Enders has Nohman, who fancies himself as an agent of the universe's natural will towards its own destruction. Although he does seem to enjoy it just a little too much.
Dwarf Fortress-At the moment, all you can do in Adventure mode is wipe out all the world's sentient life (The only reason its not all life is because animals seem to respawn). For extra fun, people often try to kill everyone with a Self-Imposed Challenge or two.
Soon this kingdom will vanish along with all who dwell within. And you, too, will sleep eternally in the dark power's embrace!
Both the Primagen and Oblivion in the Turok series.
The Darkspawn in Dragon Age were born to destroy the world of Thedas and everybody on it. The only reason they haven't is because they are also perfectly fine with attacking each other if there are no other victims. They are also compelled to seek out the Old Gods, an endeavor that usually takes centuries. Sadly, the Old Gods become tainted by the Darkspawn and become insane Archdemons that are also Omnicidal. The Archdemons are able to unite the Darkspawn and launch campaigns to wipe out Thedas known as Blights.
Darth Nihilus of Knights of the Old Republic II: The Sith Lords. At some point in the past, he began consuming the lives of others for his nourishment by draining them through the Force. By the time the player character encounters him, he has become, essentially, the Anthropomorphic Personification of hunger, has already consumed all life on several inhabited planets, and, if left unchecked, will soon do the same to the entire galaxy...and beyond.
His master, Darth Traya, sought to kill the Force itself. In defiance of the trope, it turned out, once she realized that the Force does not equal life and that people would do just as well without it and the Jedi/Sith that depended on it.
Hot Coldman from Metal Gear Solid: Peace Walker turned into one when he activated Peace Walker to not only launch a nuke at Cuba [originally Mother Base, but it was changed by one of his men], but also to transmit the false data to NORAD, and made it quite clear that, even though he hopes that they don't launch due to his feeling that this will prove that humanity is weak willed, he did not care either way.
Big BadHeiss from Radiant Historia. After seeing history full of warfare, suffering, and sacrifices (which only seem to delay the inevitable destruction) through the Black Chronicle, he decides that people do not deserve to exist and tries to bring about The End of the World as We Know It.
Ledgermayne from AdventureQuest Worlds wants to end all life on Lore by sealing off all magic from it, knows said motivation of its own, and doesn't care if all life dies off if it succeeds.
Noxus also counts as one in the same game as well. The fact that he created Vordred with Sally's help was his first step towards turning all life on Lore undead. And that's not all - his attack on Shadowfall was also part of his plan to cause the end of the world by turning everyone undead.
Kezeroth the World Ender in the 2012 Frostval event, who wants to kill off all life on Lore by bringing Quetzal's Comet down upon Lore and awakening the great beast Quetzal. He is a Straw Nihilist who believes that he is an agent of nothingness and that the universe's true nature is decay and rot, that hope is a lie and that joy such as that experienced during Frostval is a mask that all life wears to hide from the truth.
In the opening of Shin Megami Tensei III: Nocturne Hikawa succeeds in bringing about the Conception that destroys the world (although the one who does the actual destruction is YHWH, who intends to have the world recreated afterwards through a Reason). He further intends to turn this new world into a World of Silence through the Reason of Shijima. In the True Demon ending the Demi-Fiend destroys all of Creation on Lucifer's orders.
In Fate/stay night, AngraMainyu is a perfect Omnicidal Maniac, who took on the Servant form of Avenger in the third war. What's that, Avenger died and got absorbed into the omnipotent, wish-granting holy grail, giving him access to an unlimited source of miracles and magic, and the ability to swallow the planet in Black Mud whenever the Grail is used to perform a miracle? Well...fuck.
Overlord Zenon from Disgaea 2 used to be an Omnicidal Maniac in his past, but has settled down with merely being an Evil Overlord ruling Veldime in his old age. Only he turns out to be a fake. When Laharl ends up unwittingly unleashing the true Zenon from her can, she immediately tries to go on an all-killing rampage until Adell and Rozalin manage to trap her again.
StarCraft II: the Dark Voice plans to use the Zerg and the hybrids to wipe out the Terrans and the Protoss, and once they're done with that, the hybrids will kill all the Zerg so they can reshape the galaxy themselves.
The Fallout series has a few notable examples, but the most obvious one has to be the Toaster in New Vegas, who also happens to be a Harmless Villain due to being, well, a toaster (which he himself claims is also his excuse for becoming so murderously insane in the first place). A far more serious example, and far more lethal, is Father Elijah and Ulysses. Elijah wants to conquer and enslave the Wasteland with technology from the Sierra Madre, while Ulysses feels there hasn't been enough atomic holocaust.
You can, however, convince Ulysses that his motivation and goal is flawed right after it has been set in motion, and actually help you out to try and stop it. No such option for Father Elijah, however.
Villains like Shao Kahn and Onaga are out not to destroy the realms but to conquer them and rule them as tyrants forever- their favored tactic is to merge the other realms with Outworld, the realm they rule (after they get rid of each other). However, Mortal Kombat Deception reveals that they and other villains are the Unwitting Pawns of The One Being, the sentient entity that in ancient times tried to eat the Elder Gods before they defeated it and turned it into the realms (The Heavens and the Netherealm excepted). Essentially, the One Being is trying to get them to resurrect itself by merging the realms and likely end all life in said realms in the process—if Onaga had been playable, his ending would have seen him become the One Being. This is probably an Aborted Arc though, as subsequent games never mentioned the One Being again.
Scorpion, of all people, briefly became one of these in Mortal Kombat Armaggedon to get revenge on the Elder Gods in a Rage Against the Heavens scheme after they fulfilled a promise to bring his dead clan back to life...and brought them back as undead zombies. The plot of that game was that there were too many powerful fighters running around and the gods had decided to Kill 'em All by pitting them against each other in a tournament with ultimate power as the prize, because otherwise the fighters would unintentionally destroy everything with their fighting. Scorpion tried to derail the plan by killing The Chosen One, the guy who was supposed to get the power to prevent it landing in the hands of one of the villains which the next game reveals happened anyway- Shao Kahn was the winner, simply because he was pissed at them. He wanted to destroy all the realms to spite the Elder Gods, and if he could, kill them too in the process.
While nine of the Ten Wise Men in The Second Story merely seek to take over the universe, the last one, Indalecio / Gabriel, seeks to invoke the Crest (Symbol) of Annihilation to destroy the universe. If you complete some optional sidequests to learn more of the backstory, Indalecio/Gabriel is revealed to be Dr. Lantis, who went on a crazed rampage after losing his daughter Filia/Philia to a great war hundreds of millions of years ago
Luther Lansfeld from Till the End of Time becomes one late in the game. He does manage to destroy the Earth and many other planets, but decides to destroy the entire universe later on.
Avalon from Legaia II: Duel Saga attempts to use the power of the Source Forge, the beacon of creation, to destroy the world and create a new one in his image.
Avalon: I will destroy all life, leaving only me! I will be the world!
Lazarus in I Miss the Sunrise...possibly. He's a mentally unstable Blood Knight, and characters claim that he would annihilate everything in the galaxy For the Evulz if he had the chance, but when you do meet him, he claims that such things are beneath him. Given what the Big Bad's plan is, though, it's possible that he wants to permanently destroy all of reality by ascending to godhood and then preventing the new universe from being born.
Upon hearing that Taiga in Duel Savior Destiny is incapable of remaking the world and can only destroy it, Big BadDowny Reed is completely indifferent or even pleased, believing that a world that would kill his sister doesn't deserve to exist.
Paulinus in Byteria Saga: Heroine Iysayana seeks to become powerful enough to kill all mortals. Justified as he is also revealed to be the artificially created Dragon-in-Chief of a superior being who couldn't do that himself without attracting the angels' attention. That entity has few problems with it because he fully knows about the afterlife, they'll all die eventually, anyway, and he doesn't understand why mortals exist in the first place. Which brings us to his motivation: He wants to bring the Celestial Bureaucracy down, and expects that killing all mortals will successfully make it collapse.
8-Bit Theater's Black Mage. Every other strip at least mentions to his desire to kill everything in existence just for the heck of it. Luckily, as Word of God says, the universe exists to make Black Mage's life a living hell. Considering how when he died, he became the King of Hell and every single high powered magician and wizard alive immediately got the Oh, Crap signal from the universe about how the end of all reality was coming, the universe has been incredibly careful since to make sure that he never gets in that position again. Considering that this means keeping him alive (as his physical body acts as a Restraining Bolt), this means A) he has survived a lot of things that he probably shouldn't havenote like Australia dropping on him, and B) his body count keeps climbing. So ever once in a while the universe seems to like to even the score. A lot.
A Beginner's Guide to the End of the Universe has the personified SINGULARITY, which has, in fact, already destroyed the entire universe—except that the Physical God protagonist has unconsciously created a house, light and air for himself in the resulting void, thus stymieing the natural cycle of destruction, leading the SINGULARITY to send minions to kill him in hopes of eventually destroying the impudent remains of reality.
Homestuck has at least three of these. The Big Bad, Jack Noir, is, thanks to the prototyping of Becquerel, the First Guardian of Earth a Physical God who has already wiped out several worlds including two versions of his own homeworld and shows no signs of stopping any time soon. Eridan Ampora is a former Ineffectual Sympathetic Villain who harbors dreams of genocide according to Word of Godand he wants to join Jack. Finally there's Gamzee Makara, a sweetheart-stoner-turned-Ax-Crazy-psychopath who wants to kill everyone for the sheer hell of it and is apparently more than powerful enough to do it.
All three of those, however, pale in comparison to Lord English, an immortal, unstoppable monster that destroys entire universes for no other reason than because he can. Every time he unleashes his power, it causes vast, gaping cracks in the very fabric of Paradox Space itself. He is, so far, the only being capable of permanentlykilling characters, apparently able to erase their very souls from the afterlife and the dream bubbles. He even killed the author of the comic, although thankfully Hussie's ghost self has since been seen wandering the afterlife. Aranea describes it best.
ARANEA: The player is somehow also im8ued with a limitless supply of power. Enough to destroy anything he wanted, for as long as he wanted. And knowing the villain of our story, anything he wanted would 8e everything. And as long as he wanted would 8e forever.
In Kid Radd, the Pixel Art Comic masquerading as a Sprite Comic, GI Guy attempts to destroy the entire Internet and the video game escapee characters that inhabit it after realizing that their kind was created entirely for killing — which is, you know, accurate — and losing hope of change when attempts at organized societies fall into war.
He also intended to destroy every computer hooked up to the internet, believing that it would destroy society (not being sure whether humans were directly or indirectly dependent on computers). However, The Seer really takes the cake, not just wanting to destroy Earth, but believing that with all the stars and planets out there, there HAS to be life on some of them. So when he's done with Earth he will travel to one of those and kill everything there...
Though recent events have opened up all kinds of questions about this.
Also, Xykon freely admits he might fall into this himself if he gets bored enough, though at the moment he's just an Evil Overlord.
The Pa'anuri from Schlock Mercenary...Possibly. 'Attempted destruction of all Baryonic matter in the Milky Way' certainly qualifies them for the trope, motivated by Baryonic entities (sentient life forms) using transportation lethal to them.
Misty Snow/Mother Hydra in the Cthulhu Mythos saga Shadowgirls is a power-hungry sadist who doesn't care that raising her consort Dagon will unleash the imprisoned Old Ones and destroy all reality.
K'Z'K, originally known as Kozoaku, is the Mohkadun god of Destruction. He is meant to be part of the cycle of creation and destruction, allowing the world to be reborn every so often. But he is overly enthusiastic about his job, not only bringing extinction events before they are meant to occur, but also wanting to destroy the world permanently. To stop him from destroying the world prematurely, God empowered Krohnus into divinity. K'Z'K has been struggling ever since against Krohnus's Web of Fate, and his cultists aim to release him to bring about the end.
Aylee's species are a Horde of Alien Locusts, but they take it so far as to destroy entire planets after consuming everything on them and before spreading out further on the remains, and at least one of their leaders, Leono, sees it as their species' religious duty (as opposed to just a way of feeding and multiplying) to do so. In his belief, the universe has spiralled out of the control of its Creator from the start, and She has sent this species to consume it.
In Goblins, the villain of the 'Maze of Many' arc is a psion from another reality, who plans to divide by zero in such a way that everyone within the Maze will be erased from existence.
SCP-682 is a strange, seemingly-reptilian "creature"—the term "creature" can be used only loosely, as it doesn't seem to be alive in the sense we usually think of—that considers all living things disgusting sub-beings that must be destroyed. Well, all of them except Creepy ChildSCP-053, which it was discovered to be oddly fond of. No one's quite sure why it reacts differently to SCP-053—and they're too scared to take advantage of it, as keeping an Omnicidal Maniac prone to fits of Unstoppable Rage and a toddler that induces Unstoppable Rage then instantly kills anyone that hurts it in the same room seems like a bad idea. His reasons for this hatred for all life aren't directly stated, but are implied to be a really extreme version of Humans Through Alien Eyes. This has become sort of a Running Gag, as the SCP Foundation's researchers are so afraid of 682 that they're constantly trying to find some way to kill him, no matter how insane.
It might be because SCP-682 knows, somehow, that 053 can kill him, and thus resists her abilities to avoid death. It is Dangerously Genre Savvy, and has survived countless assassination attempts because of its knowledge of their abilities.
It could also mean that 053 is somehow vastly different from other living things in our universe. Enough so that 682 doesn't feel homicidal towards her. Humans, on the other hand, do feel that way.
SCP-1370 has the attitude of an Omnicidal Maniac. Its ability to do anything about it, however...
SCP-076-2, "Able", will kill anything and everything on sight for fun. The Foundation's attempt to weaponize Able went horribly wrong because they treated him like a human being and not the superpowered murder machine shaped like a human that he really is.
O'Malley, the Big Bad of Red vs. Blue, is an over-the-top parody of this trope. His goal is to take over the universe and "crush every living soul into dust. Um, except for you, Vic. You can be assistant crusher."
Alternatively... "I will eat their hearts and crap out their souls! They will taste oblivion! Which tastes like Red Bull. Which is disgusting!"
Season 12 plays it straight with Control, a mysterious member of an unknown group that wants to kill everyone on the planet Chorus. Co-Dragons Locus and Felix also qualify as they seem all too gleeful to follow along with Control's orders.
This is the desire of The Entity in Atop the Fourth Wall which converts and consumes universes into itself, travelling between them, hoping to absorb the multiverse. I goes by another name... MissingNo.
The eponymous Big Bad of the Sonic fan animation Nazo Unleashed, is one, since he aims to detonate the Master Emerald and destroy the planet in the process.
Unicron from Transformers, particularly in Energon. He wants to eat the multiverse, one planet at a time, one timeline at a time, one universe at a time. Not because he's hungry, like Galactus whom he resembles, but because existence is somehow offensive to him. Megatron/Galvatron may be considered an accessory to the crime(s).
Anyone who willingly works with Unicron also counts. This list includes:
The Fallen, one of the 13 original Transformers whose job is to monitor the end and rebirth of the universe, but got way too fascinated in the "end" part;
This is Megatron's actual goal when the last part of Transformers Cybertron rolls around. He wants to use the black hole and the Cyber Planet Keys to destroy the universe so he can rebuild it in his own image. Somehow.
Unicron, curiously, actually succeeded on at least on occasion. Then slept through the Big Bang that recreated it. He was not amused. He has also stepped up his game of late - said black hole is apparently replicating across realities and growing.
Daemon from ReBoot initially seemed to just be a supervirus corrupting countless programs to The Way, which turned them into her loyal slaves. However, the climax revealed that she intended to connect herself to everything, before initiating a program that would destroy herself and everything connected to her, ending all strife and conflict in the peace of oblivion. This is what she is programmed to do; so whether or not she's truly a maniac or just following her programming is up for debate.
The Brains from Futurama. These unbelievably powerful, mindraping giant brains appeared in this universe milliseconds after it came into being. Their one goal is to gather all of the information in the universe, then destroy it so that no new information will ever appear. The only real opposition against them comes from the Precursors, the Nibblonians. Unlike typical Planet Looters, the Brains actually enjoy their omnicidal campaign. The Brains are Brainiac from the DCAU but they're a race, not just one evil AI. Thanks to there being no Superman to fight them, the Brains come close to succeeding.
Lucky for humanity, Fry was immune to their mind powers. Then he made them leave the Earth for no raisin!
Later on, the Brains build the Infosphere to store all the information in the universe. Naturally, they plan on destroying the universe once they finish learning everything. Fortunately, Fry and the Nibblonians manage to stop them again.
Danny Phantom becomes this in an alternate future. Most fans certainly see it that way. Fortunately, this is averted... hopefully. It's made pretty clear that even though the exact circumstances of the change were averted, it's still possible.
Spider-Man: The Animated Series: an alternate-universe Peter Parker, already unbalanced due to questioning his identity and losing his Aunt May in that world's version of The Clone Saga, is possessed by a world-hopping Carnage symbiote. Spider-Carnage decides that life is meaningless and attempts to wipe out the multiverse, forcing Madame Web and the Beyonder to assemble a team of alternate Spideys to stop him.
The Heys from The Tick. Played with the usual tongue-in-cheekness of the series, but their motivations are purely omnicidal.
Darkseid from The DCAU has the ultimate goal of obtaining the anti-life equation and using it to undo the current existence, so he can rebuild it in a manner more to his liking. Unfortunately it tends to be overshadowed by his 'torment Superman' schemes.
Brainiac, also from the DCAU, acts to destroy all of creation, but this is due to his programming rather than any genuine malicious wish to do so. That does change when Lex gets mixed in with Brainiac.
Owlman in Justice League: Crisis on Two Earths wants to kill "Everyone who ever existed or will ever exist" and destroy all reality because he feels it is the only "real choice" one could make, as for every choice one made, all other possibilities played out in another universe.
Unfortunately for Owlman that is already a lost cause, as an infinite number of universes can exist and not just those determined by mere human interaction. There would be numerous other universes where Owlman brought his Q.E.D. bomb and either succeeded or failed in any number of different ways, so he would not have even destroyed a fraction of the entire multiverse.
To put it in perspective there are universes, in Owlman's words, "so similar to each other that you could spend a lifetime searching for any difference", such as those that differ by the location of an atom in a Planck time.
The Fairly Oddparents has two. First, Dark Laser really wants to blow up the Earth because...well, it's there. A more serious example is The Darkness, a powerful and ancient entity who has destroyed countless worlds, including Turbo Thunder's home Wonder World and Yugopotamia.
The Darkness is more a person (well, consciousness) of mass destruction. It just wants somebody to love it, but everyone keeps attacking it, so it defends itself, and is better at defending itself than the planet it was trying to defend itself from is at hurting it.
It was fairly heavily implied that, unlike the rest of the show's villains (who were merely greedy for power or wealth), Blight was actually completely insane - she was certainly the only one pursuing pollution for its own sake.
Trigon of Teen Titans had the explicit goal of destroying "the world of mortals", though he did plan on remaking it in his own image afterwards. As this would mean a literalHell on Earth, it doesn't make him any less evil than the others on this list.
Utrom Shredder wasn't so into the destruction of reality at first. He just realized that the Ninja Turtles would persist in every reality so winning in one really meant nothing in the grand scheme of things. What he wanted to do was eliminate the TMNTs from existence, by destroying them on Turtle Prime (the original Mirage comic). Reality was shattering but only after he had left the 2003 dimension (which he didn't know was happening). Once he saw that the destruction of the 1984 Turtles would in fact break reality fully, that's when he threw down the gauntlet and decided reality would have to end if it meant he could win.
Note that he was willing to do it knowing fully well it would also destroy his daughter, Karai, who is arguably the only other living being he ever truly cared about. That goes to show how badly he'd gone off the deep end.
US President EvilLex Luthor goes this route in Superman/Batman: Public Enemies, after injecting himself with a Kryptonite/steroid cocktail that increases his strength but at the same time causes him to go insane. When the US Military is unable to stop the Kryptonite meteor, Lex chooses to allow the meteor to collide, believing that he will be heralded as the savior of the few survivors remaining.
Killface of Frisky Dingo begins the first episode filming his statement to the world that he intends to use the Anihilatrix, a giant engine, to fly the Earth directly into the sun. No motive is given. Fortunately for the Earth, he used all his money building the machine, and does not have enough money to actually broadcast his message or get the Anihilatrix working.
And when he did get it working it only moved the Earth a few feet. And cured global warming.
In the Earthworm Jim cartoon, Evil the Cat aspires to destroy the universe.
Ultron in The Avengers: Earth's Mightiest Heroes, albeit with the twist that his first body has been programmed so it cannot harm the Wasp. He gets a new body and can bypass this later. He nearly nukes the entire world. The robot is likely one of the scariest villains to emerge from the show thus far.
The Lich from Adventure Time. It's said he converted the life force of the planet into energy for himself with the intention of destroying the world. His sole desire in the world is to destroy all life. Unlike most villains in the show, this is played dead seriously with him. There's a reason this guy is the Knight of Cerebus and the single most terrifying monster in the show.
Season 5 reveals why: the Lich is the by-product of a magical nuke used during the Mushroom War and thehuman in the epicenter. The Lich is effectively a sentient weapon of mass destruction continuing its mission.
The Ice King actually dips into this in "A Glitch Is a Glitch", trying to use his computer worm to destroy all life within the CGI episode. Of course, he's just doing it because Princess Bubblegum said she'd only date him if he was the last person on Ooo (or so he says), rather than just for omnicide's sake like the Lich.
The Shushu of Wakfu. The only reason their king wants to invade the main characters' world is because the Shushu have already destroyed everything worth destroying on their own world. Destruction is nothing but one big game to the Shushu.
Negaduck: Crimes?! Who cares about crimes?! I'm into mindless wanton destruction!
Firelord Ozai, the Big Bad of Avatar: The Last Airbender, becomes this in the Grand Finale. While he had conquered the majority of the Earth Kingdom, the war was far from over and Zuko said that the Earth people will keep fighting as long as they have hope. The solution? Burn the entire continent, and construct a new Fire Nation upon its ashes. Granted, it was Azula's idea, but still.
In Family Guy, Stewie's evil(er) brother Bertram traveled through time to murder Stewie's ancestor (who turned out to be Leonardo da Vinci) in a Terminator-style scheme. Unbeknownst to him, due to a Timey-Wimey Ball Stewie was accidentally responsible for the Big Bang and, thus, creating the universe, and thus his actions ended up destroying everything, except Brian and Stewie who managed to survive by stepping outside of normal time and space. When they go back to stop him, they try to reason with him by telling him that he will destroy everything if he does this - Bertram thinks for a second, then declares "WORTH IT!" and tries to kill Leonardo anyway. He succeeds, but Stewie creates a Stable Time Loop by taking his place.
Aya on Green Lantern: The Animated Series becomes this in the second half of season 2 when after Razer denies he's in love with her due to her resemblance to his late wife, she rips off the head of then-current Arc Villain the Anti-Monitor, integrates with his body and takes control of the Manhunters on a quest to rid the universe of emotional beings. She starts out small before deciding that to do this she needs to recreate the universe, going to the center of it and modifying the events of time so that emotional beings are never created and her drones are put in their place. She changes it back at the last moment when she comes to her senses after Razer is mortally wounded.
Terrifyingly, Zhang Xianzhong may have been the first (and only) Omnicidal Maniac in Real Life history, back in the 1640s. He 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, while a few of his last loyal servants carved a massive stone which "explained" his actions: "Heaven brings forth endless things to benefit man. Man has nothing with which to repay Heaven. Kill. Kill. Kill. Kill. Kill. Kill. Kill." The stone came to be called the "Seven Kill Stele", and even after the Manchus put Zhang to death, everyone was so terrified of it, they refused to touch it, even to destroy it, until the 1970s.
To put the effects of Zhang Xionzhong's reign of the Shichuan region into some kind of perpective, 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 regin, only 16,096 adult males were registered, and Chengdu was said to have become a virtual ghost town frequented by tigers.
The human body's immune system is this when you think about it: it is one of the most efficient killing machines in nature, and it exists to divide the universe into self and non-self and kill everything that consists of non-self.