Mayuri Kurotsuchi) the The eponymous character from Clown. As far as fictional serial killers go, he is one of the most vile, evil creatures ever conceived. Mayuri tricked Ichigo's mother into going to an abandoned warehouse to talk about her son. A scene was not dedicated to it, but it is explained that she was brutally murdered, gutted, and then hung from the roof by her own intestines. Ichigo is also led to the scene where he discovers his mother. He feeds someone through a mulcher, eats children, and horrifically tortures most of his victims.
Jashin was one when he was alive. He was a cruel and merciless Warlord who killed any who stood in his path, butchering entire countries and people years ago before the main timeline. He even used his own son as a Sacrifice to create a Summon which requires a hundred Sacrifices each use. He had no Freudian Excuse like others, he simply killed because he could. Eventually The Sage of Six Paths confronted and killed him but it got worse as his remaining followers deified him and vowed to continued killing all in his name.
And in the Present time line Worshiphers Hidan and Keiji Sosano are just as bad. Hidan betrays Akatsuki and murders dozens of ninja and people and nearly kills Kakuzu and attacks Konoha with followers. Keiji takes over Earth and proclaims that they will start a Fourth Ninja War and that they proclaim an Age Of Jashin where all will worship him or be killed. Hidan even tried to go back in time and kill Naruto and change the past when he was born and see to it that Kyuubi destroys Konoha and would've if Orochimaru hadn't stopped him from doing so. Keiji willingly sacrificed thousands of troops in battles and killed the woman who loved him just so his plans wouldn't go unnoticed and be able to put put his final plan into action.
Janita: Air Jay is a psychopathic Viking who kills people on a whim with his unique fire abilities. He was a mercenary in the Third Ninja War, killing a thousand people, before being sealed by Naruto's parents, Minato and Kushino. Upon being unsealed by bandits he burns them to death, and kills several more when informed him that Minato and Kushino have been killed, believing only he is allowed to kill them. Air Jay joins Takuma’s plan to unearth the weapon to destroy the village. Air Jay massacres a village as they try to fight back with pitchforks laughing about how easy it was, is about to kill a child when Hinata tries to stop him, considers killing Hinata in front of her daughter, the eponymous Janita, until he smells Naruto on her and takes her alive as bait. When Hinata wakes up she finds herself in a trap rigged to kill an innocent girl if she escapes. He later pulls Hinata down just to kill the girl. He sends eight bandits to kill his father for knowing his weakness, despite refusing to disclose it. Air Jay repeatedly torments and kills the slaves, having a woman tell them about all his actions and tells them she will die in ten seconds if they do not work harder only to kill her when he reaches six, takes two prisoners and asks Hinata which one he should kill then kills them both when she cannot decide, and has them all burned to death. He then loads up weapon with bombs to destroy the entire Leaf Village, unlike Takuma who simply wanted to kill the leader, Hiashi, and take over. He then drains Takuma's Chakra to power the machine telling him he intends to keep Hinata to abuse.
Team 8, the author's interpretation of Itachi Uchiha seems to fit the bill. Unlike canon, he committed the Uchiha Massacre simply to test himself (as he originally claimed), but in-story his complete Lack of Empathy makes him one of the most deplorable individuals. In particular, when he crosses the Moral Event Horizon even further by killing Kurenai (showing absolutely no remorse or even emotion at having done so), his partner Kisame Hoshigaki - himself a renowned Blood Knight - is freaked out and disturbed by it.
Tobi from War Of The Biju is the Big Bad and the Man Behind the Man to Nagato. Before convincing Nagato to create Akatsuki, he was Madara Uchiha's Dragon. Tobi was originally from a sect of the Uchiha Clan who rejected the truce between the Uchiha and Senju that formed Konoha...and its Sole Survivor. Why? He murdered them all, including his parents, younger siblings, and even lover so there was no competition. When Madara gave his final orders, preparing to die in his sleep...Tobi smothered him to assume the role. One of the things that stands out is how he framed the Uchiha Clan: while dueling Minato the Yondaime Hokage, he simultaneously led the Uchiha Clan on a wild goose chase, merging with the clone he used right after the control of Kurama, the Nine-Tailed Demon Fox. All so the Uchiha would be away right as Kurama got big Sharingan's in his eyes when the clan was gone right in front of the entire Konoha leadership. Then years later when after the Uchiha Clan began working amicably with the Village again he reappeared and blackmailed Fugaku Uchiha...after literally Mind Raping several women to death. All so he could get the Uchiha's support for the coup. Which he then helped Itachi put down. Finally he starts the most destructive War in the entire history of the Five Great Nations. Seeing everything but a big game to kill as many people as possible, Tobi lacks anything and everything that would make him sympathetic.
Jacob Waterknot from Tilting the Balance is willing to kill and slaughter people for his own gain. The line crossing is when he plays a card that, in normal game terms, call down several a dozen meteors and destroy the field. However, he made the duel as real as it could be. The meteors were real and destroys a good portion of St. Paul, killing countless people just so he could attempt to defeat one person.
Yu-Gi-Oh! Forever has several villains, both those who serve as the Big Bad of their respective arc and those who are henchmen, but none come quite as close to utter vileness as Abel Drake, a member of the Quirky Miniboss Squad in the JUDAS arc. He mind-rapes children (using the Millennium Key's power to unlock and alter memories as he sees fit) For the Evulz, forced one character to relive her Dark and Troubled Past using said ability, and had a very bad impact on another major character's screwed-up development by stealing that character's mother's soul to power the revival of an Eldritch Abomination, then brainwashed said character and his sister so they wouldn't remember that part of their past.
The Blood+ fanfic Nobility has Didier, who will kill anybody who supports Anjou. At first, it appeared that he simply wanted to become the chiropteran king. However, it is revealed that he had several chances to kill Anjou, but he disregarded them in favor of Mind Rape.
From the Neon Genesis Evangelion fic Nobody Dies, we have Iruel. Eldritch Abominations are generally exempt from Complete Monster status due to Blue and Orange Morality and other such things, but Iruel manages to overcome this because he is considered repulsive and horrific even by the other Angels. During a synch test, he traps the pilots and Mana in a Lotus-Eater Machine and turns their dream worlds into nightmarish manipulations of their worst fears. The only thing keeping the chapter from being 100 percent horror is Rei's scenario. None of the other Angels had any particularly negative sentiments to Iruel's death, and when they learned there was a possibility that he was still alive, their immediate thought was to kill him before he does anything.
The fake Gennai. What he does to Mimi is quite possibly the most disturbing act of callousness in the entire franchise (canon included).
Daemon definitely counts as well. There is nothing he cares about more than inflicting as much suffering as possible, and he is perfectly willing to slaughter thousands, including a seven year old girl, in order to get what he wants.
The Nightmare is another example, an Ax-Crazy, digital Humanoid Abomination that delights in causing pain to others so that it can enjoy their reactions. Takato even says that it's worse than D-Reaper
Fedt-geszhine, of Yukari Is Free. Currently holding the highly-coveted title of "Most Evil Character", Fedt-geszhine is the bespectacledDragon of Warmaster, the head of the Veluszhi Imperial Army. Fedt is a genius who is currently working on his life goal: learn everything. He once locked himself in a cage with an angry, rabid animal just to see if his regeneration serum worked (It Did). He isn't above using living human test subjects for his experiments or just for fuel for the bio-reactor. And when he was a child, he killed his mother, just so he wouldn't get in trouble for drilling a hole in his baby sister's head.
Mobile Suit Gundam's Prince Ghiren Zabi was never a nice guy to begin with. However, it could be argued that his character boiled down to his desire to conquer the earthsphere. Zeon Quest, however, shows what Ghiren is willing to do in order to rule, from masterminding the notorious Operation British, fully aware of the massive civilian casualties it will cause (and it's hinted that he lied to his family and allies to get it approved), to trying to nuke neutral civilians so his rival siblings will get blamed, to blowing up a friendly island just to ensure his forces will have a monopoly on producing advanced mobile suits. And much like his canon counterpart, Ghiren has no problems with killing his father to stop a peace treaty (and his own prosecution for war crimes). But in this fic, he also shows that he has no problems killing off the majority of supporters as well, and his plan to sell them all out to save himself. His obsession with conquest at any cost turned him into The Caligula.
Sweet Tooth from Holy Musical B@man. He gleefully murders people using various sorts of deadly candy but doesn't become a Complete Monster until he reveals his final plan: he kidnaps Robin and sends a video message out to Batman, telling him that he has Robin and has started a Facebook poll asking Gotham to choose-either Robin dies or Sweet Tooth poisons the water supply. And if Batman tries saving Robin, he just poisons the water anyways. And he's never given any motivation, which means that this horrible Sadistic Choice and all his other crimes are most likely For the Evulz.
The demonic Cobweb, who imprisons Sleepwalker in Rick Sheridan's mind as part of a larger plan and later Mind Rapes one of Rick's friends into committing suicide less than two days after Rick's birthday.
FeverPitch, a Manson-like cult leader and serial killer who voluntarily transformed himself into a fiery skeletal monstrosity as part of his divine crusade.
Jack the Ripper, who returns to terrorize New York City in the twentieht century.
Jack O'Lantern, a costumed psychopath who sees himself as The Unfettered and commits ever-escalating crimes mostly For the Evulz and developed a crazed obsession with his teenaged nemesis after Spider-Woman kept interfering in his "fun".
The Big Bad Red Cyclone. He's a cunning and charismatic talker and one of the two griffins responsible for starting the entire conflict. He sees the ponies as wimps and wouldn't like to think of them as anything else other than an extinct race. When he reveals his Evil Plan to General Silverbeak, his concept is rejected. What does Red Cyclone do? He kills the general and takes over the command over the griffins. Then, he blames everything on the ponies, sending his soldiers to burn Equestria down and exterminate or enslave all ponies! And he does it all because he thinks the world doesn't need the weak.
Gilda becomes one by torturing Rainbow Dash and breaking Medley's wings anyway just to spite the former.
The Joker in I'm a Marvel... And I'm a DC, starting with his Moral Event Horizon. After finding out Harley was secretly helping the Green Goblin, the Joker shoots her. Later, after tricking the heroes into thinking The Punisher shot him, the Joker leads Harley away as they try to escape. The Joker assures Harley he wasn't going to leave her there to die...and then hits her to the ground, saying this is a much better spot. When he comes back from the dead in Rorsarch and Deadpool 2, he kills a mook who sold him out in a very painful and thankfully offscreen manner, then shoots Rorsarch.
Alexia from Ranma ˝/Sailor Moon Crossover fic The Return uses Mind Rape as a recruitment tool, turning unwilling humans into her compliant, loving daughter Succubi, and then gleefully abuses, discards, and uses them as Cannon Fodder; after all, it doesn't matter if they die - she can always make more. Of the villains so far, she might not have been the biggest, but certainly the scariest due to her ability and willingness to strike at our heroes' sense of identity and security. She also caused the most pain and suffering and was considered appalling even by the standards of other demons.
Shinji And Warhammer 40 K has a surprise example with Kaworu. He is directly responsible for the deaths of millions of people and sees nothing wrong with, say, dissolving helpless humans into a formless lump of biomass or twisting them into mindless daemons, managing to surpass both the Angels and SEELE combined in sheer cruelty. Making it worse is that he genuinely believes he is working towards the Greater Good, but actions speak louder than words.
Mecha Sonic in Super Mario Bros. Z. As soon as he came into being (via Metal Sonic absorbing past models into himself), he destroys the Death Egg and forces it to crash-land on Mobius, causing an apocalypse. He then, while hunting down the Chaos Emeralds, also took the opportunity to kill Sonic's friends in extremely brutal ways (Tails by strangling him, Amy by beating her up, Knuckles by beating him up and then filling him up with machine-gun processed lead, and Cream and Cheese by apparently blowing her head off), and had wiped out most, if not all, of the planet's population and turned almost half of it into a burning wasteland. He was also the reason for Shadow's currentpersonality, because he murdered Rouge and Omega, the only people he could call his friends. As soon as he arrived at the Mushroom Kingdom to recover the Chaos Emeralds, he also killed a Goomba who found a Chaos Emerald simply because he didn't give it to him, even though there was absolutely no way he could have known that was a Chaos Emerald. He then mercilessly beats up Yoshi to gain his chaos emerald (and says that he would have killed Yoshi anyways even if he did comply to his request). He later brutally killed both the Koopa Bros and the Axem Rangers X and destroyed Yoshi's Island. Not just scouring the surface, but hitting the island with a Sphere of Destruction so violent that it vaporised the entire island.
The Smooze from the G1 movie is reimagined as the S'muz, an omnicidalEldritch Abomination that seeks to devour the multiverse and absorb the psychokinetic energy it believes other life-forms have "stolen" from it, is gleefully willing to torture anyone that gets in its way, and refuses to stop until it's the only thing left in all of existence.
In the sequel Mines of Dragon Mountain, Tirac — the villain from the G1 special "Rescue at Midnight Castle" — is likewise reimagined as an ancient demon who feeds on negative emotions (hate, despair, etc), and thus started a war on Equestria half a million years ago in order to feed on those emotions on a global scale, a war that wiped out several species, leveled continents, and killed most of Equestria's gods, before he was sealed away. In the present, he corrupts and possesses Gabbro, turning him into a Knight Templar, before attempting to fully escape his prison by wiping out a city and feeding on the pain of the deaths of thousands (if not more). And that's not even counting the murders, tortures, and other sick stuff he does purely for the sheer joy of it. Also, giving him bonus points for both shows; first, it's revealed that he's also TheBeast, and then the epilogue reveals that he's Discord'smaster. So, yeah, he's one evil bastard.
Severus Snape. As Headmaster, he inflicts his sadistic whims on the poor students and regularly blackmails the D.A. by punishing eleven-year olds in their place. He even ordered an eleven-year old flogged and left in chains for thirty hours. What Snape did to Michael as a punishment for freeing this kid was completely unforgivable: he had the poor guy tortured in a nightmarish way, prolonging the agony to the point where his best friend Terry tried to put him out of his misery with Avada Kedavra. The author has been criticized for portraying Snape as way, way too evil.
"Professor" Hans Belsen, named for the Belsen-Bergen Concentration Camp. If Grindelwald is an Expy for Adolf Hitler, then Belsen is an Expy for Josef Mengele.
In Notebooks And Letters, Severus Snape. Although helping the trio and the others escape from Malfoy Manor, he refuses to do so until Harry drinks a specially concocted potion that will completely wipe out every pleasant memory Harry has, until he is ultimately left with nothing but his self loathing and a seething hatred for the entire world and all of those he once loved. Snape sees this as his ultimate revenge against James Potter, having refused to accept any responsibility for losing Lily, and as seen in a pensieve memory, relished that Harry would have to die against Voldemort and had asked Dumbledore if HE could be the one to kill Harry. When the group have escaped, Snape slaughters any survivors and burns the mansion down with Fiendfyre, and then kills himself so as not to face any repercussions.
In the Deliver Us From Evil Series, Culverton Smith is shown to be even more of a monster than he was in the Canon, and is even mentally labeled this by Holmes. Smith goes around infecting people with his deadly tropical diseases just to study the results, then murders hisstep-nephew out of Greed for his stepbrother's estate (an action on which Moriarty actually calls him out). Then he gloats over a dying Sherlock Holmes, and this rewrite of a canonical scene is actually pretty painful to read. All this makes his eventual fateimmensely satisfying.
In A Study in Regret, MoranshootsWatson as payback for Holmes being the cause (directly or indirectly, the story never elaborates) of Moriarty's death. Moran proceeds to subject Holmes to Cold-Blooded Torture for well over a month, then allows Holmes to be rescued so that the detective can heal just enough to watch helplessly as Moran murders Mary Watson and her (as-of-yet-unborn) baby (this last part has not happened yet - merely been deduced by Holmes to be Moran's plan). All this to get back at Holmes for Moriarty's death.
Brynn from the Battle Royale fan fic, 72Hours. She orders the Brat Pack to assault Lenore, Damien's girlfriend, and shaves her bald. Later, during the prom, when Damien went to give Lenore her corsage, Brynn replaced the flower with a lock of her hair, convincing Lenore that Damien was behind the attack. This not only causes her to break up with Damien, but also drives him to play the program and become the deranged Carrie-Gollum-Jason combo he becomes, with his first targets being the Brat Pack.
Most versions of The Joker qualify for this trope, and the Joker from The Joker Blogs is no exception. To name a few of his crimes, he kills people on an almost regular basis, held Lisa Arkham hostage and threatened to kill her if her husband Dr. Arkham didn't comply, kidnapped and tormented both Nurse Pearl and Lyle Bolton, and gradually manipulated Harley until she snapped.
Red Dawn +20 has many terrible villains, with the biggest and baddest of them all being the GRU's GeneralSergeiKhvostov, aka "The Butcher of Clear Lake City." His worst offense, the one that got him his nickname, is upon arriving at Johnson Space Center in Houston and finding that NASA had managed to move everything (personnel, equipment, documentation) out of there before the invaders arrived, leaving only a mocking note "Catch us if you can,". He responsed by ordering the massacre of the families of NASA contractors, astronauts, and anyone else left behind in Clear Lake City. He also bathed a Cuban officer (one of his nation's allies) in battery acid when they got into an argument over a mistress; massacred the town of Freer, Texas in response to an assassination attempt (that's implied to have actually been carried out by other elements of the KGB who found his methods counterproductive); and forced the mayor of San Antonio to kill one of his staff, threatening to rape her and then kill her himself anyway if he didn't. (He complied).
Face The Music by Elm22 has two of them. Reuben Shelling is the primary one, but the other guy, Denaglio, borderlines it as well. They kidnap Grissom by first kidnapping Greg and telling Grissom, prompting him to give himself up to keep them from harming his young friend. The guys brutally torture Grissom, beating him, using a bullwhip on him, and tormenting him with roach clips in his skin. They also repeatedly rape Grissom and force him to perform on them. He's finally rescued, but left traumatized and terrified,with awful PTSD and all the typical after effects of this type of abuse. Sadly, that isn't the end. Denaglio is shot during the first rescue, but Shelling gets both Grissom and Sara again, capturing Sara and using her as bait for Grissom, and tortures both of them, first targeting Sara to torment Gil. He then turns on Grissom after Grissom tries to protect her by begging him to leave Sara alone and torture him instead. Shelling was driven by Grissom sending his brother to jail, and both villains have dark, abusive pasts, but between Shelling's past history with abuse of women and the horrors they inflict on Grissom...*shiver*. And this fic is *very* well-researched in regards to the after effects of such abuse and very well written; the author is very talented, which makes it all the more haunting to read.
The same author also wrote a kidnap fic called Thirty Minutes And Counting where Gil is kidnapped by Office Fromansky, a character from a fifth season episode. Try reading about Gil's feet getting numerous nails driven through them, plus the other abuse he took, and not getting sad for him.
Bob Garrison from Cold Case Season 8 has a sadistic love of torture, tries to kill a witness for watching him torture a man to death, and, finally, in his crowning act of evil, he has his men murder and frame a recovering alcoholic in order to trick people into thinking his murder was a mugging.
Cheryl/Drew is introduced as a seemingly normal college freshman that befriends Miley at Stanford until is revealed in the final chapter that she was the one who orchestrated the explosion that killed Oliver and 8 other people just because they advanced farther than her on American Idol. She is given a somewhat sympathetic backstory in that her father was killed in a car crash, until she reveals she gave him a drug that would give him a heart attack so she could pay for her college. She even kills her minions when she no longer needs them, including her dragon, Professor King, who she was revealed to be cheating on Lilly with throughout the whole story.
Another monster is Martin (pronounced Mar-teen). He kills his brother in the same explosion because he was The Unfavorite, and mocks his death on Facebook. He also vandalizes the Music Tech room for no reason.
Dark Specter. The first story is primarily concerned with his rise to power, and we get to see exactly why he earned the title "Grand Monarch of Evil". While having innumerable wars and genocides behind him in his quest for Dimension Lord-dom is bad enough, it's the sheer overkill he applies to our own humble blue marble, it being prophesied to birth his destroyers, that truly pushes him into this territory. Two instances in particular stand out. In the second story, he's been revived and took the galaxy's government, but he's heard that Zordon is also on his way back to the realm of the living. Specter kidnaps all the various babies he thinks might be the reincarnated Zordon, as well as Karone, to confirm their identity. When Karone tells him that none of the babies he has are Zordon, Specter blows up the room full of babies, then teleports Karone back to the Rangers...with her throat cut. Karone gets better, but we're never told if the babies do. The second instance is in a flashback in the third story, where it's revealed that Specter sold advanced alien tech to the Nazis in exchange for them turning Earth over to him when they were done conquering it. They failed to do that, but one can only imagine how much worse he made World War II. He's also behind everyone else on this list, by the way. Interestingly enough, the early parts of the first story give him a bit of a Woobie-ishBackstory that casts him as a former Ranger millions of years ago who accepted the proto-United Alliance of Evil's offer to become their leader so he could get justice for his murdered girlfriend, but the author has gone on record as saying he's grown unhappy with this backstory and plans to write it out next time he revises the fic.
Which brings us to King Ra. He's the absolute dictator of a race of Lizard People and a high-ranking member of the UAE. He claims to have genetically engineered humanity to be his race's slaves and wholeheartedly believes this gives him every right to abuse them in any way he wants, and does he ever. As it turns out, he's lying through his teeth, but it's then revealed that he's responsible for the Dominus Lords' control of Earth, so he still believes humanity "owes him". Naturally, few tears are shed when the Rangers cut him down, with him whining about how "ungrateful" humans are all the while.
This next one is a big spoiler. It's Captain Logan, the apparent Big Good from Time Force. How bad is he? Well, it turns out that Year 3000's mutant crime wave problem was actually engineered by him, as a way to unite the people against a common foe and distract them from the dictatorship they're living under. Oh, and he shot Ransik's wife on the day their daughter was born, which drove Ransik back to crime just as he was about to completely atone from killing Dr. Fericks due to The Power of Love. He's also a nigh-unkillable Super Soldier. You can't help but cheer when Ransik jams a vial of liquid magnetite (the Super Soldiers' one weakness) down his throat, causing him to crumble to dust in an extraordinarliy painful-sounding way.
Then there's Senator John Thorne, leader of an anti-alien hate group. We realize he's this right around the time he has a refugee camp massacred. Most of his private army, used to perform the aforementioned massacre among other things, appear to qualify, too, but as they're just Mooks, it's hard to tell.
There's also Jacob Russell, an Amoral Attorney-turned-Corrupt Corporate Executive. He bought out one of BioLabs' subsidiary companies and turned it to evil. Not only that, he murdered Trini's Uncle Howard (a character fans of the show would recognize) when he wouldn't sell his research to him, making the death look like a suicide. It's even sort of hinted he greased the authorities' palms so they wouldn't consider the fact that Howard had never displayed suicidal tendencies before.
The Tracker fic "In Sheep's Clothing" had a complete monster Cirronian, an anomaly in a normally gentle species. He kidnapped and tortured Mel until Cole got to them. There was skin carving and dry ice burning involved. It prompted the normally fairly nonviolent Cole, a Cirronian himself, to pound the villain until Mel coaxed him not to sink to the guy's level and just collect him already.
Two Slayers - One Heart, a Buffy the Vampire Slayer fanfic, gives us a Complete Monster version of Amy Madison, who sets traps designed to kill very young slayers, watchers, and people she's never even heard of— all because those people are friends of Willow Rosenberg, whom she hates psychopathically. She also gets turned on when she discovers that her girlfriend, despite being built like the proverbial brick house (and a psychopathic murderer in her own right), is only thirteen years old. Amy even whistles cheerfully as she prepares to sacrifice a seven or eight year old girl in an attempt to bring back the First Evil and open a new Hellmouth.
Dredd, the commanding Ape in the Tall Plains area in The Legend of SpyroRetelling: A New Beginning, fits this big time. His Establishing Character Moment is trying to get information out of Kane by dropping one of Kane's tribesmen to his death from several thousand feet. He then tells Kane he intends to kill as many of the Atlawian Tribe as he has to in order to get the information he wants, happily adding that he might use some of them as target practice. What does he want? The few, very minute mining deposits they have left that the Ape hadn't already pillaged from them. He only gets worse after his Villainous Breakdown when his Bad Boss tendencies begin to kick in...
The Legend of Spyro: Zonoya's Revenge incarnation of Malefor is even worse than his canon counterpart, and that's saying something. To start, he has the newly corrupted Cynder slash out Zonoya's, her best friend, eye and left her thinking Cynder betrayed her, making Zonoya's grudge on Cynder his doing. This means he's indirectly the cause of all the horrible things Zonoya did. The emotional Mind Rape he subjects her to. And let's just say his plan to destroy the world could be considered merciful to his vision of ruling it.
The fanfic Fortitude gives us Ashton who plans to force Zelda to marry him and also plans on "breaking" her. He stops at nothing to try and kill Link, he never cares about anyone, and he even '' has Heather whipped because Zelda ran away for three days.
In the fan movie The Legend of Zelda: The Sage of Darkness, we have Davik, Link's uncle and also the titular villain. He seems to train Link in the ways of the Hero, only he's really attempting to feed Link hatred and anger in order to speed up Ganon's revival, even supplying him with the White Sword, one of Ganon's artifacts. He's also manipulating Ertegun for his own agenda, and it is also hinted that he also plans on betraying Ganon as part of his agenda as well. He also brutally murdered Link's parents as well as poisoned his own sister. The reason? None whatsoever, aside from possibly trying to get Link to go down the road of hatred even more. And his real plan is to extinguish the Cycle of Eternity, which may result in the destruction of the entire world, for no reason besides hating it for unspecified reasons. He's also a psychopath.
Raker the Jackal, from a Sonic the Hedgehog ficseries by JudasFM. First appears in Caves of the Ancients, before which he sold Tails out to a slave mine, and before then, killed his father, leading to his mother's suicide by drowning, and has been abusing his brother Bait (at least that's what he renamed him) ever since. While Sonic, Knuckles, and Bait head to the Scrap Brain Zone to save Tails, Raker stalks them the whole way, and blows up the Oil Ocean Zone during one of their confrontations. When Sonic calls him out on this the next day, his response is to casually say he didn't stop to think things through. In the next fic, he teams up with Knuckles' thought-to-be-dead mother and Dr. Robotnik, in hopes of getting Bait back, just so that he could torture and kill him (as it's revealed after he retrieves him). Getting him back also involved blowing up a building with Vector inside. Robotnik finds his actions just as appalling as everyone else. Bait is the only one who has any respect for him, because of "family loyalty", even though Sonic tries to get through to him that Raker does not return this. It speaks volumes when even Sekko, who runs the aforementioned slave mine and ordered Knuckles' lost sister dead before being killed himself by the person he asked to carry it out, cannot hope to compete with him.
Ashura, from A Rose and a Thorn. In part III of the ficseries, Shadow sets out with Espio to free him and Mirage from the ARK, after having learned about them at Prison Island. However, Mirage tells Espio upon being freed that Shadow must be insane to set someone like him free. She doesn't simply fear what will happen; she knows how evil he is. Upon being freed, he sets out to find all of the Chaos Emeralds, stopping none short of hurting Eggman and Rouge for two of them and causing the latter to miscarry Sonic's baby. At the end of the fic, he manages to kill Espio and blind Mirage. Starting in the next part, Sonic helps Mirage travel back to the time she was created on the ARK, so that she can kill Ashura in order to save Espio. It is within this part that he shows how really bad he can be, from his interactions with Black Doom, to mindraping Midnight.
Master Samuel from The Adventures Through Runescape. He crossed the line early on in the story when he kidnapped, gruesomely tortured, and murdered a Herblore mage just so he could get the recipe for his potion. It's a crowning moment of awesome when his hand is sliced off by Haru while trying to get the second ingredient of his potion, although his right-hand James ultimately replaced it with some claws. And then he gets worse. He forces Dream Decay to betray Mainiac97 by holding his girlfriend hostage, brutally tortures him with the God Rune, and kills Dream Decay right in front of Mainiac97. It's a pretty sweet moment when he gets what he deserves near the end of the story.
The Paper Mario: The Thousand-Year Door fanfic Better Off Alone has Beldam. Not only does she pick on and abuse Vivian for every little thing that goes wrong and give Vivian mental damage in the form of low confidence and self-esteem, but then she plans to take over the world and kill Vivian and her friends. She makes Vivian believe that her friends were just using her! When confronted about it, she simply says, "You say that as if it's a bad thing." Yikes!
From Kingdom Hearts fic Fill the Moon we have Larxene's husband who would lock his wife in a box for three days without food, clothing, or water, just for not cleaning properly or some other petty offense. He's also implied to have raped her with a knife, bitten her, burned her, beat her, and threatened to cut off her breasts. While Hollowmoon and Kingdom Hearts have the excuse of being Eldritch Abomination monsters and thus not subject to human morality, Larxene's husband is absolutely human and absolutely monstrous.
The charming, genial Yuuka Kazami. She will (and does) kill people for mildly annoying her, enjoys "games" (i.e. brutal torture), and absolutely loves children, all because it amuses her. She is unpredictable enough to often leave people alive inexplicably, but there is a reason everyone in Gensokyo voids themselves at the mere mention of her name.
The Shadow Youkai is no slouch either. Essentially the Anthropomorphic Personification of death and destruction, it delights in havoc and carnage, but, even rendered relatively powerless, demonstrates an incredible fondness and proficiency for Mind Rape as well, shattering the mind of one of its "captors", and is motivated by nothing but raw sadism.
The Team Fortress 2 fanfic Respawn Of The Dead gives us RED Spy. Not only did he play his own teammates like a fiddle (planning their deaths, to boot), he also made sure to get Soldier and Heavy killed first, just to make it easier to get rid of the others (and, in the case of the latter, convincing him to die for Medic's sake), locked Medic and Pyro in a room full of zombies, and then invited Engineer to help him rape Sniper.
It seems that even the Tales Series fandom is big on having evil characters if the fangames are anything to go by. Tales of a Twist, a parody of Tales of Symphonia, gave the protagonists elements of this trope. Colette delights in watching the suffering of people relatively early on. While the dialogue tries to play all of this for Comedic Sociopathy, it doesn't really excuse the fact that they blew up a Human Ranch with the humans still inside it. Tales of the Ocean, however, doesn't play this for laughs. The main protagonist turns out to have been Evil All Along and was responsible for drowning the entire island he grew up on because of the racial prejudice against him, and the only thing he regrets is that his Morality Chain got hurt. All those hundreds of deaths on his head? The fact that he smiles while telling you all this should say it all.
Gavin Buildmore from Ashes To Dust by Canzet Yote. He's a Corrupt Corporate Executive crocodile who is Slick Possum's abusive boss. When Slick was 5, Buildmore tortured him by sticking a rose in his mouth and yanking it out repeatedly, and on Slick's 6th birthday, Buildmore beat his mother to an inch of her life with a lead pipe. He then forced Slick Possum into child labor and repeatedly beat him with chains and choked him. One time, when Slick was a teenager, Buildmore crushed an innocent duckling to death in front of him and mocked him for crying about it. He also brags about how he stole Slick's mothers life insurance money to buy a yacht, and once he found out Slick was gay, he mocked his sexuality by raping him repeatedly. And that's only his backstory. When he arrives in the actual fic, he implodes the theater while protestors are still inside, killing innocent men, women, and children just so he could build a brand new theater. He then kidnaps Marcia and tortures her to death with dry ice, and when Slick, Shifty, and Nutsy go to rescue her, he captures Shifty Dingo and threatens to rape him while holding a garden shears to his throat and fondles Shifty's genitals. At one point, he lets Shifty and Nutsy escape the mansion, only to try and chase them down in a helicopter, and he actually manages to shoot Shifty in the leg and laughs about it. He also orders his goanna minions to gangrape Slick Possum. Oh yeah, and he sells his own daughter into sex slavery. The worst part about all this? He gets off scot-free!
The eponymous character from the now taken down fanfic IEAB. Let's see, it makes Dib and Gaz go borderline insane, destroys a planet and more than 80% of it's race, murders Zim's love interest and her unborn babies, and then proceeds to track down Zim back to earth and half-destroys Earth as well. It feels no remorse for any of this.
Iggins, the Big Bad of the second story in the My Hostage Not Yours trilogy. He's pretty mild compared to others on this list, but his vendetta against Gaz — which starts with sending assassins after her and her loved ones and escalates to using a Mind-Control Device to make her his slave (with some disturbing subtext to his intentions for her) — is all a result of Gaz taking his Game Slave 2 when they were kids. And he stole it from her in the first place. Oh, and when Dib and Zim attack his lair to free her, he first uses his own younger siblings as bodyguards, and when Zim gets past them, forces him to fight Gaz — which, seeing as Zim and Gaz are in a relationship by this point, adds a whole extra layer of Kick the Dog to that action. When Gaz breaks free of the mind control and proceeds to beat Iggins within an inch of his life, which renders him catatonic and promptly locked away in a mental institute, it is very satisfying to read.
Both Heian Chao and Wu Xiu of A Different Lesson take this trope and run with it gleefully.
The acts Chao perpetrates are especially, and truly, unforgivable, and they only get worse as the story goes on. Countless murders (including of children), Demonic Possession, More than Mind Control, forcing friends and loved ones to kill each other, unleashing demons from the spirit world, necromancy, corrupting people's souls and intentions, pushing Tai Lung into committing his rampage, planning to make People Puppets of the whole world, all so as to live forever and force his vision of perfection on everyone else.
Xiu, meanwhile, killed her own father just for being "weak" and good, framed Jia for it so she could twist and manipulate her into obeying and serving implicitly as an assassin, longed to have the same powers Chao had so she could do the same things he did, poisoned countless soldiers who had been fighting the Huns, murdered her teacher, tried to manipulate Tai Lung into joining her with lies about his family (and also helped plant doubts regarding Shifu and Oogway's love and pride in him so he would fixate on the Dragon Scroll to earn them), nearly killed Po and Tigress, did kill Zhuang, loved the feeling of Chao's dark chi and wished to bathe in it when everyone else was sickened and terrified by it... And both of them enjoyed every bit of what they did, with no remorse or regrets, and no sign they could be redeemed or ever would be.
Necromancers Of China Saga, gives us the leader of the necromancers, Jasmine Crescent. At first the necromancers are introduced as Well Intentioned Extremists who are trying to end all conflicts. Towards the end of the first book, we learn that the necromancers are all pawns and their leader is using them to gain power all to herself. Her real goal is to sacrifice fifty males and fifty females to absorb their souls and become a master vampire. She's also incredibly manipulative, shown when she tricks Po and Tigress into believing she's a friend, so she could trick them into helping her get the job done faster. She also decieves Po and Tigress daughter from the future, convincing her into manipulating her own parents in both the future and the present to further keep the facade going, then trying to kill her once she doesn't need her anymore. She also has several Kick the Dog moments, such as murdering the family of her defeated foe, trying to kill her own childrensimply for standing up to her, and destroying Gongmen City just so collecting one hundred souls would be a little easier. She also succeeds in killing Shifu, and A Million Is a Statistic is completely averted, as the saga takes the time to show the aftermath of her deeds and givin us a glimpse of just how badly she ruined people's lives. There are several more atrocities she commits, but these are the worst.
We have an elderly Azula in a world where Ozai succeeded in conquering everyone. She finally hits her Villainous Breakdown with the realization that there is no way she can escape her impending death from old age, so she decides to go out in a blaze of glory, starting a war that will probably kill a good percentage of the world's population, and also set things up so that she'll be remembered as a hero who tried to stop that war.
Gian is a ruthless and sociopathicBounty Hunter, who doesn't care who is in charge of the world order or who his employers are, so long as he's paid for his services - which involve murder. He forces a rather meek young Earthbending slave to help him uncover the rebellion base, and kills her in cold blood simply because he had no further use for her. He's also revealed to be an Earth Kingdom man who essentially exploits his own people for profit, and admits as much to Jiazin without an ounce of guilt about it.
The Total Drama Island fic Lost and Found has Gwen's dad: he abducts Gwen's mom and brother and sets her home on fire to fake their deaths so that Gwen ends up living with him, and once she gets there, he starts beating her daily and cuts her whenever she tried to do something about it, threatens to kill Gwen's mom and brother who he had locked up so that she'll do whatever he'd tell her, shoots a maid in the face with no second thoughts because she tried to stand up for Gwen, and it was revealed that he only had her around so he could use her to make money off via modeling gigs and having her win a season of Total Drama. He meets his end when the girlfriend he betrayed and killed after she grew a conscious shot him in the chest before she died.
In the Phineas and FerbDark FicSnapped, which was later taken down by the author, Isabella Garcia-Shapiro, surprisingly becomes this. After years of Phineas unknowingly ignoring her for Ferb, Isabella finally snaps and plans to take her revenge on Ferb. She kidnaps him, graphically slaughters him, and gives him a serum that allowed him to watch her take his organs out. Before this, she revealed that she killed multiple children and classmates before Ferb and tells him what she's planning to do to him. After Ferb's murder, she calls Buford, Danville's resident bully, to where she was at, knocks him out, ties him up, and puts him in the closet. The fanfic ends with her about to use Buford as a scapegoat for Ferb's murder and telling Phineas that he was responsible for his half-brother's demise.
The Lion King Adventures: The Writer is responsible for all the bad things that happen in the story, and is the true villain of the entire series. The Writer created the world Simba and his friends lived in, and had caused every evil act in that world. The Writer also created all the other villains in the story. The Writer's creations included Scar, as well as evil versions of Timon and Pumbaa who drain the souls of cubs. He had always been trying to kill Simba and his friends or ruin their lives for fun, and at the end of the series, he goes into the world himself to kill Simba and his friends so he can take over and rule the world for eternity as he destroys thousands of lives for his own amusement.
In Paul Robinson's The Locust, the character creates a mind control device, finds a businessman, then uses his device to get the businessman to borrow several million dollars and take out $200,000 in cash. While they're waiting, the man's beautiful 15-year-old daughter comes home from school. The character takes her upstairs and convinces her she's in love with him. Then he has sex with her. When the cash arrives, the character takes it and the businessman's wife and daughter with him and tells the businessman to wait for a phone call. The character uses his device to convince them to leave, then takes the wife and daughter to a hotel suite (which the wife charges to the businessman's credit card), calls the businessman, and starts having sex with his daughter again while the businessman has to listen to it. As he's about to climax, the character gives the special command over the phone that causes the buisnessman to believe life is worthless and he wants to die and puts a gun to his head and shoots himself. The gun goes off over the phone at the exact moment the character climaxes. Then later, he collects the assets from the family and pimps out the mother and daughter as well as lots of underage girls.