Though Magneto is a villain against the X-Men group, he has since in the comics joined them a lot of times, even becoming a hero himself, though he is not a supervillain due to his morals - he is an Anti-Hero because he protects mutants from humans at any cost. Several times, he could be compared to civil-rights leader Malcolm X.
Lex Luthor is a major antagonist in DC Universe Online and acts as the mentor for villains who choose the path of the "metahuman" (genetic-based), he is also notable as being one of the prime villains of an alternate future in which he successfully kills Superman only to have Earth invaded by Brainiac.
In "The Death and Return of Superman," still one of the best-selling collected stories of all time, Doomsday, a genetically engineered Kryptonian weapon, cuts a path of destruction across the Earth, culminating in a life-or-death showdown against Superman in Metropolis which ended, unfortunately, in death.
Born before the current Marvel universe came to be the young Galactus escaped death when his universe came to an end via merging with the Cosmic-Egg - resulting in him being reborn into the new infant universe as the mighty Galactus - devourer of worlds. as time went by Galactus would create numerous Heralds to seek out suitable worlds for him to devour, the most famous of his many Heralds was the Silver Surfer - who would rebel against Galactus in defense of the Earth and be replaced by Nova.
Ra's al Ghul is one of the main antagonists in the Batman series. He is probably one of the most intelligent and mysterious villains that Batman ever faced, since he is nearly immortal and legendary. Not much is known about him, which gives him the advantage in a confrontation.
In recent years, the Kingpin has evolved from a typical mob boss and comic-book villain to a complex and conflicted character. He has attempted to retire from crime life and has even spared Spider-Man's life after promising his fiance to no longer be a criminal.
Catwoman (real name: Selina Kyle) is a major supervillainess of the DC comics' Batman franchise. Created by Bill Finger and Bob Kane. Catwoman is a seductively sneaky female burglar and a jewel thief who dresses like a cat and carries a bullwhip while performing her thefts.
Two-Face (Harvey Dent) is a fictional supervillain appearing in American comic books published by DC Comics, commonly as an adversary of the superhero Batman. The character was created by Bill Finger and Bob Kane and first appeared in Detective Comics #66 .
Thaal Sinestro, simply known as Sinestro, is a fictional character from DC Comics and the main antagonist of the Green Lantern franchise. He is one of the greatest and most powerful members of the Green Lantern Corps, leader of the "Sinestro Corps", and arch-nemesis of Hal Jordan, John Stewart, The Lantern Corps and the Guardians.
Brainiac is an alien android appearing as a major antagonist in DC Comics. He is regularly portrayed as one of Superman's arch-nemesis (a trait he shares with Lex Luthor and General Zod) due to his actions on the planet Krypton and has gone on to become one of DC's most dangerous and formidable foes since his debut.
Raven Darkholme, (also known as Mystique), is the major villainess from the X-Men comics and media. She is a somewhat cruel and treacherous ally of Magneto who has worked as part of the Brotherhood of Evil Mutants but has also taken over - being capable of even more radical thinking than Magneto at times.
Bullseye (Lester) is a fictional character appearing in American comic books published by Marvel Comics. A psychopathic assassin, Bullseye uses the opportunities afforded by his line of work to exercise his homicidal tendencies and to work out his own personal vendetta against Daredevil.
Doctor Octopus (real name: Otto Gunther Octavius) is a major antagonist in Marvel Comics, serving as one of Spider-Man's most dangerous and recurring villains, as well as his secondary archenemy. He is a genius supervillain and former atomic scientist who can control four mechanical arms grafted onto his body.
Mister Sinister (real name: Nathaniel Essex) is an enemy for The X-Men, Cable and Deadpool and a powerful supervillain mutant whose bent on creating / becoming a being of genetic perfection and forcing the world's populace into the next step of evolution by weeding out those he believes are weak.
General Zod is a fictional supervillain appearing in American comic books published by DC Comics, commonly in association with Superman. The character, who first appeared in Adventure Comics #283 (April 1961), was created by Robert Bernstein and initially designed by George Papp.
Professor Eobard Thawne, otherwise known as Harrison Wells and the Reverse-Flash, is one of the main antagonists of the Arrowverse, being the main antagonist in the first season of the CW's television series The Flash, a major recurring antagonist in subsequent seasons of the show, while also appearing as the main antagonist in Season 2 of the spin-off series DC's Legends of Tomorrow, and a major antagonist in the Arrowverse crossover Crisis On Earth-X.
Bane is a fictional supervillain appearing in American comic books published by DC Comics, commonly as an adversary of the superhero Batman. The character first appeared in Batman: Vengeance of Bane #1 (January 1993) and was created by Chuck Dixon and Graham Nolan.
Writer Garth Ennis created one of the most colorful comic book villains of all time when he conjured up Herr Starr, foe of Preacher protagonist Jesse Custer. A former German special forces solider, Starr is recruited by the Grail and tasked with recovering Custer - but he has plans of his own.
The original Shredder made his debut in the original Teenage Mutant Ninja Turtles comic books, published under Mirage Comics. However he has since made notable appearances in Archie Comics, Image Comics and several other publishers as the TMNT franchise expanded.
Baron Heinrich Zemo is a powerful Nazi scientist and soldier and a major villain of the superhero Captain America and the Marvel Comics universe as a whole. He was the founder and original leader of the original Masters of Evil and the main villain of any storyline involving them.
Mongul is a powerful alien supervillain from DC Comics, the ruler of War-World and one of Superman's greatest foes, though he has also been seen in other media without the Man Of Steel (for example a toned-down version of Mongul was seen in the cartoon series Batman: Brave and the Bold).
Talia al Ghul is the daughter and right-hand of Ra's al Ghul and a lover/enemy of Batman. She traveled the world with her father and learned numerous skills from him. Talia is also Batman's love interest but her loyalty to her father keeps them from being together. She would occasionaly betray her father and help Batman or vice versa.
Dr. Harleen Frances Quinzel, better known as Harley Quinn is a super villainess from DC Comics. She is the Joker's self-proclaimed girlfriend and henchwoman. Harley Quinn is eccentric and extravagant, and usually commits crimes with a sadistic glee and hyperactive energy.
Thanos was ranked number 47 on IGN's top 100 comic book villains of all time, 22nd on Wizard's Top 100 greatest villains list and number 21 on Complex's 25 Greatest Comic Book Villains list. The only being, other than Lady Death, who Thanos respects and considers a friend is Adam Warlock despite the many times he helped the heroes of Earth fighting him.
Mephisto, sometimes using the name Mephistopheles or even Satan (among many others) is a powerful demonic super-villain from Marvel comics and is one of several such demons that feed off humanity's belief in The Devil so as to masquerade as Satan himself.
Post-Crisis, with the restart of the universe as one thanks to the machinations of the Anti-Monitor, a simpler, more streamlined DC Universe seemed imminent, with characters acquired from Charlton Comics, Fawcett Comics, and Quality Comics all becoming incorporated into the new DC Universe.