Adventure Time: The Lich is an Evil Sorcerer who desires nothing less than the extinction of all life. While most of the series' antagonists have sympathetic moments or funny quirks that add levity to their crimes, the Lich is the only villain to always be played absolutely seriously. His attempts at wiping out all life has included possessing Princess Bubblegum, going One-Winged Angel, and rampaging through the Candy Kingdom; killing and possessing the body of Billy as part of a complex gambit to get a Reality Warper named Prismo to grant his wish for the extinction of all life across The Multiverse; murdering dream Prismo as well as Prismo's physical body, the latter solely For the Evulz, then breaking the universe's worst criminals out of their cosmic jail, all in order to create an unstoppable army for himself to lead in wiping out all life, one planet at a time. The Lich is also heavily implied to have been involved with the destruction of mankind and one of the reasons why the show takes place in a world After the End.
Ben 10: Ultimate Alien: Aggregor was an Osmonian warlord who was wantonly murderous in his quest to achieve omnipotence. Aggregor killed aliens by absorbing their energy and matter to gain their powers. Generally this caused his victims to turn into desiccated husks, but for his plans to become powerful enough to reassemble the Map of Infinity he turned five aliens into energy and absorbed them into himself. Aggregor killed Magister Prior Gilhil by stabbing him in the back, killed two other Plumbers by sucking them out into space, and absorbed the life and powers of a pacifistic alien just because he could. His two most vile crimes, however, were when he nearly destroyed an inhabited world by stealing a component from the device that kept the planet from breaking apart, and when he attempted to kill and absorb a baby alien capable of Reality Warping to complete his ascension into godhood.
Courage the Cowardly Dog. Katz's motives tend to change due to the show's Negative Continuity, but what he does is always horrible. In his first appearance, he ran a Hell Hotel where he fed all his guests to spiders, taking sadistic delight in doing so. In a later episode, he ran a health spa where he transformed his guests into machines and forced them to fight for his own amusement. In both of these appearances, he didn't seem to get much gain for these actions, but did them all with a Slasher Smile on his face. In short, he's an Ax-CrazySerial Killer played straight...on a kid's show! What makes Katz even worse is the fact that the family is heavily implied to just be the latest in a long line of victims to fall into his clutches.
Van Kleiss is the ruthless dictator of Abysus. Though he uses propaganda to claim he's trying to build a better world for E.V.O.s, in actuality Van Kleiss cares only for his dream of world domination, and nothing for his subordinates. Van Kleiss makes a habit of petrifying E.V.O.s by sucking the nanites out of them, or turning regular people into E.V.O.s to act as muscle for him, not caring that such an action could leave them permanently transformed. In his bid for power Van Kleiss murdered Rex's parents, experimented on his Woobie, Destroyer of Worlds follower to amplify her powers while causing her excruciating pain, and threatened a little girl to force her father to turn the people of New York into his zombie army.
Dr.Branden Moses from season 2's "A Family Holiday" announced a breakthrough in nanite research that allowed him to dramatically reverse E.V.O. mutations, giving a faux demonstration using an E.V.O. and either an actress with a set of prosthetic tentacles or an E.V.O. with tentacles, playing the part of the "cured E.V.O." Having convinced hundreds, possibly thousands, of people (including Dr. Holiday, who added her sister Beverly Holiday to Brandon's ranks) that he had made a breakthrough, dozens of intelligent but physically deformed, incurable E.V.O.s lined up to be cured. Instead, they were kidnapped and brought to a lab in the Arctic circle where their mutations were amplified and were ready to be auctioned off to the warlord with the deepest pockets.
Hot Wheels Battle Force 5: Krytus, the 3rd Big Bad, is known as the most malicious being in the entire multiverse (this was said byanotherBig Bad!) and evil incarnate. He restarted a eons old war between the Red and Blue Sentients simply because he saw the Blues as weak and inferior and desired to conquer the entire multiverse. When Sage froze the Red Sentients, the war continued and Krytus carried out a genocide on the Blues. At one point, it's revealed that he had several thousand Blue Sentients tortured to death and the one who managed to enter hibernation to escape him was punished by having his body sabotaged, dooming him when he woke up. Krytus's first action after being freed from his prison is to throw the one who released him off a cliff! He then spends most of the series trying to kill Sage (his own sister), who is a pacifist who only wants peace. At one point, after being forced into an Enemy Mine with Vert to escape the Shadow Zone, he sets up an ambush for Vert the moment they're out of it, unlike previous villains who normally had the honor to let the Battle Force 5 go after an Enemy Mine. Not even the other villains are safe from his wrath, as he starts an Enemy Civil War among the Vandals through Grimian. But what solidifies this is at the season finale, when he and Sage finally have a confrontation. After asking Sage Was It Really Worth It? to imprison the Red Sentients, she replies that if she hadn't, Krytus would've endangered not only the Blue Sentients, but the entire multiverse. Krytus actually agrees with her, fully admitting that not only does he know what he's doing is evil and wrong, he doesn't care so long as he can conquer the multiverse. The only reason he tried to free the Red Sentients was because he wanted an army to conquer the multiverse with, not out of concern for them.
Jonny Quest: The Real Adventures: The Monster of the Week from ''Eclipse" was the succubus/vampire known as Elise Lenior. Appearing as an innocent young woman on the run from evil men, Elise maintained her youth and beauty by draining the life from beautiful, innocent women. The man hunting her had lost his sister to her years past. Elise murdered the men who tried to tail her, and later mind controlled Hadji into her slave to bring Jessie to her for her food source. When her right-hand man protested about Elise trying to replace him with Hadji, Elise declared he was right and sucked the life from him as well. When her deadline of an eclipse was approaching, Elise abandoned all pretense of charm and subtlety and assumed her monstrous true form to kill everyone around and drain Jessie's life.
The Powerpuff Girls: Season 4's two-parter "Knock if Off" has one-shot villain Professor DickHardly. Introduced as the sleazy college roommate of Professor Utonium, Dick quickly sees the potential of the Powerpuff Girls as a way to get rich quick. Getting the girls to supply him with Chemical X, Dick makes his own knock-offs of the girls and starts a business selling these copies as superheroes. Due to Dick's greed, however, these knock-offs have been created with minimum materials and Chemical X, meaning that, even though they are aware, they are mentally stunted and physically deformed. When the effort of superheroing causes the knock-offs to fall apart, Dick's happy because it means he gets to sell even more copies. At one point Dick notices one of his knock-offs is a perfect Buttercup copy, his response is to order the girl melted down for her "excessive" Chemical X. The episode's climax has Dick capturing the real Powerpuff Girls and killing them slowly by draining them of their Chemical X. When Utonium offers to be a slave, making Chemical X for Dick for the rest of his life, if Dick will let the girls live, Dick only laughs and says he'll kill the girls and keep Utonium as a slave. Greed incarnate, Dick Hardly was notable for being the only villain on the show to be played completely seriously, with no humorous quirks to detract from his viciousness.
Zombie Island: Jacques stands out as a stark contrast with his two Woobie, Destroyer of Worlds co-conspirators. While his partners had no idea that praying to their cat god for help in their pursuit of vengeance would lead to their transformation into monsters, Jacques was a normal man who willingly became a monster to make himself immortal. For years he's been using his ferry to escort people to Moonscar Island, only for him and his partners to drain the life from them. Afterwards their victims are left to wander the island as zombies, aware but unable to move on to the afterlife.
Mystery Incorporated: The Bigger Bad, the Nibiru Entity, is a member of a normally benevolent inter-dimensional alien race called the Anunnaki; his own kind considers him the most evil member of their entire species. He's spent untold centuries corrupting and manipulating the people around him, especially the Team Pets of mystery solving teams, by perverting his species' ability to use animals as mediums to communicate, all working towards freeing him from his prison. In the process he's ruined and ended countless lives through his Unwitting Pawns (including Professor Pericles, who the Entity turned into a murderous psychopath) without a second thought. When he's finally released in the Series Finale, he proceeds to gleefully eat his loyal minions alive along with Mr. E. He follows this by turning Crystal Cove into Hell on Earth and devouring the entire town with sadistic glee, planning to move on to the rest of the universe when he's done, all for the sake of power. When Mystery Inc. finally kill him, erasing him from time in the process, we see what Crystal Cove would've been like without his influence: a normal town with everyone living good, happy lives, showing just how much pain and misery he was truly responsible for.
The Secret Saturdays: V.V. (Vincent Vladislav) Argost is the Faux Affably Evil nemesis of the Saturday family and, in actuality, a cryptid himself. As the Himalayan Yeti, Argost murdered people for pleasure, preying upon the humans who wandered through the mountains and taking "souvenirs" off their bodies. Two of his victims were Drew and Doyle Saturdays' parents. When confronted with this, Argost only says he can't be bothered to remember all of the people he's killed. Throughout the series, Argost was obsessed with finding Kur, a god who had the power to control all cryptids. Eventually, Argost discovered that Zak Saturday was Kur himself, and so Argost began plotting to steal the boy's power. Eventually Argost managed to succeed in this by draining the god power out of Zak Monday, the evil alternate dimension counterpart of Zak Saturday; this had the side effect of killing the boy. With his newfound powers, Argost ordered his cryptid army to wage war against every major human capital city, with the ultimate goal to Kill All Humans and rule all cryptids. Though already possessing a god's power, Argost craved more power still, and so he killed Zak Saturday to drain his power as well, just as he did to Monday. Ever the showman, Argost took to committing atrocities with a theatrical flourish and dry humor, relishing the screams of his victims and considering the destruction of mankind as just another one of his grand performances.
Sym-Bionic Titan: General Modula was originally a reasonable, heroic man, but all of the good traits Modula once had withered and died when his former best friend, the King of Galaluna, mistakenly left him for dead. Possessing now only a lust for vengeance against his former comrade, and a thirst for conquest, Modula betrayed his homeworld to the Mutradi monsters and slaughtered and enslaved its inhabitants. Fearing that only the princess of Galaluna, Illana, can restore the hopes of the planet's people and have them rally against him, Modula sends countless monsters to ravage the planet where she's hiding out. It's made clear in the show that the buildings and cities his monsters destroy are not conveniently empty, and at one point Modula goes so far as to send a living bomb capable of wiping out a planet to earth all so he can kill one girl. While seemingly stoic on the outside, in actuality Modula is utterly Axe Crazy and is willing to kill anyone, even his own minions, at the drop of a hat. Instances of this can be seen when he smiles as he snaps the neck of a resistance fighter and when he casually vaporizes a minion who had failed him without even getting up from his chair.
Totally Spies!: Helga Von Guggen is a greedy fashion designer who makes "seamless" fur coats by kidnapping innocent people, injecting them with a serum that turns them into Petting Zoo People, then skinning them alive in what appears to be a giant industrial crusher. She brags about one of her coats, claiming that it's "genuine lawyer".