Monster / Mega Man

"Hehehe... That's the face... The face of rage, suffering and humiliation...It's my greatest pleasure...A pleasure only a ruler can fully appreciate!"
Dr. Weil (Dr. Vile in the Japanese), Mega Man Zero 4

Complete Monsters from the Mega Man franchise

Super Adventure Rockman
  • Ra Moon is a malevolent alien supercomputer who landed on the Earth in a distant age. An arrogant sociopath who viewed the peaceful early humans as beneath him, Ra Moon sought to exterminate them by giving them the capacity for hate and violence, leading to swathes of humans slaughtering each other in bloody conflicts. Eventually growing bored of their violence, Ra Moon went dormant for twenty thousand years before waking up in the modern age, his genocidal ambitions still intact. Manipulating Dr. Wily into helping him by reviving his fallen robots, Ra Moon generates a deadly EMP wave with enough power to destroy all of the Earth's technology and allows Wily to use it to blackmail the United Nations, all the while deceiving him into believing that it's less destructive than he thinks. At the end of the game, Ra Moon reveals his deception by torturously attacking Wily's robots and declaring his master plan: killing all humans and robots alike so he can replace them all with machines made in his image. His brand of villainy shocking even Wily, Ra Moon proved to be the most heinous foe that the original Mega Man ever faced.

Mega Man X series
  • Maverick Hunter X: In this adaptation of the first game, Sigma, as shown in the prologue OVA titled "The Day of Sigma", was once a noble high-ranking Maverick Hunter dedicated to protecting Reploids and humans alike, until he became fanatically obsessed with unleashing the potential of all Reploids, particularly in X. To satisfy his psychotic curiosity, Sigma begins orchestrating false flag operations by hiring criminals to cause towering Mechanaloids to go berserk and attack Reploids and humans alike, before killing them to cover his tracks. He goes on to slaughter all the staff at a prison to spring the psychotic Maverick Vile free and recruit him into his ever-growing army of rebellious Reploids, some of which, like the honorable Storm Eagle, are strong-armed into serving him. Right when he's about to launch all the missiles stored in a remote base, X and Zero attempt to stop him only for Sigma to grab Zero and use him as a Human Shield, while sadistically goading the pacifistic X into shooting him and sacrificing Zero in the process. When X refuses, he almost kills Zero and grabs X afterwards. When X still can't bring himself to fight back, he disarms at Sigma's request, only for Sigma to launch all the missiles at the highly-populated Abel City, killing thousands and reducing it to rubble while nearly killing X as well. The OVA ends with Sigma psychotically laughing at the burned out ruins of Abel City, fiendishly excited for the war he started due to his traitorous actions, and eagerly planning to Kill All Humans to make way for the Reploids.
  • Command Mission: Among the Rebellion army, a faction of extremists and anti-villains, the Reploid Silver Horn sticks out as a sadist on a perpetual power trip lacking in any of his compatriots' redeeming qualities. Warden of the Tianna POW camp, Silver Horn viciously kills many dissenting Reploids himself during the Rebellion's takeover of Giga City, personally torturing the famed hero Steel Massimo into a limbless, barely-living heap and keeping his mangled body underneath the camp. Forcing the Navigator Reploid Nana into acting as a sysop for the camp under the threat of executing all of the POWs, Silver Horn's response when he's finally confronted is to gleefully reminisce on his torture and eventual murder of Steel Massimo to his successor and revealing his ideals that the weak only exist to serve the strong.

Mega Man Battle Network
  • Dr. Regal is a Card-Carrying Villain and the leader of the organization known as Nebula. To prove his belief that Humans Are Bastards, Regal has his organization devoted to converting the world to evil by causing wars and spreading as much misery as possible. He subjects Lan's father to horrifying Cold-Blooded Torture and gleefully turns innocent NetNavis into servants of evil, slowly corrupting the whole Net. His end game is to connect the souls of everyone in the world to Nebula Gray, a program he created from the darkest thoughts of people, and corrupt the entire planet. At the end of the fifth game his father, Lord Wily, the notorious leader of a cyberterrorist organization, pulls an Even Evil Has Standards moment and subjects him to Laser-Guided Amnesia to destroy his evil personality and force him to reform.
  • Anime-only character Slur, The Dragon to Big Bad Duo, is both a Knight Templar and a Complete Monster. Slur is fanatically devoted to exterminating all evil from the universe...where by "evil", she means everyone who doesn't agree with her master's extremely draconian concept of morality. In other words, Slur wants to kill all humans just because she doesn't like us. And unlike Duo, Slur has no sense of fair play - she deliberately "sabotages" the Humanity on Trial plot of Stream by giving Asteroid Navis to evil people, so that Duo will be convinced that Earth doesn't deserve to live. Vicious, sadistic, and with no redeeming qualities at all, Slur might very well be the vilest Battle Network villainess ever.

Mega Man Zero
  • Dr. Weil, known in Japan as Dr. Vile, only appears in a few games, yet.is notable for being one of the most evil beings in the entire franchise. Following the peaceful resolution of the Maverick Wars by the sentient superprogram, the Mother Elf, Weil decided that Reploids needed to pay for their crimes. To this end, Weil corrupted Mother Elf by turning her into the Dark Elf, and triggered the Elf Wars. Weil used the Dark Elf and her children, the Baby Elves, to control Reploids and force them to fight each other in massive battles, which resulted in the deaths of 90% of all Reploids and 60% of all humans. Defeated, exiled and transferred into a mechanical body for his crimes, Weil eventually returned one hundred years later, consumed with a thirst for vengeance directed at all life for the perceived crimes against him. Weaseling his way into becoming the supreme ruler of Neo Arcadia, Weil turns it into a dystopian hellhole. When he breaks his citizens to the point where they're desperate enough to risk escaping into the wastelands to form their own colony, Weil decides to obliterate their new home with a Kill Sat. When his Kill Sat is disabled, Weil attempts to drop it upon the colony, killing everyone in the region. Cruel, megalomaniacal and displaying an unprecedented level of sadism in the series, Weil reveled in the suffering of others and desired nothing less than to make human and reploid alike feel like their existences were living deaths.

Mega Man Star Force
  • Gemini, from the first game, is a wicked FM-ian who despises all other forms of life, both organic and EM-based. A destruction-loving sadist and advisor to King Cepheus, he took advantage of the kingís paranoia by convincing him to destroy Planet AM, their neighboring world. When they discover Omega-Xis stole the key to activating Andromeda, their planet-destroying superweapon, to Earth, Gemini was among the FM-ians sent to reclaim it, secretly plotting to destroy Earth and take down Cepheus. He finds a compatible human in Patrick Sprigs, a boy abandoned as a baby who suffers from a violent split personality named "Rey." He takes advantage of this, manipulating Patís feelings and other half, convincing him to destroy humanity by merging with him to form Gemini Spark and use Andromeda themselves while using their powers to make humans attack each other. When one of his allies, Queen Ophiuca, is defeated by Mega Man and begs him for help, Gemini responds by killing her on the spot. Heís eventually defeated, but his manipulations of Pat and Geo convince the latter to abandon everyone in his life for a time. Heís later revived when Cepheus decides to use Andromeda, putting Gemini in charge of stopping Mega Man. He attempts to destroy the machinery needed to help Mega Man reach Cepheus, suggesting heís fine getting himself killed to destroy the Earth. Upon his defeat, he asks Cepheus to destroy the planet to avenge him. Loyal only to himself and his love of destruction, Gemini is Star Forceís poster child for Aliens Are Bastards.
  • Mr. King is the leader of the organization Dealer, and the Big Bad of the third game. Appearing to the world as a benevolent millionaire who donates to charity, Mr. King is actually a Manipulative Bastard willing to use anyone for his own benefit. As the operator of Joker, all of Joker's crimes lead right back to King. In addition to forcing his own Wizard to self-destruct to defeat his enemies, King adopted orphans and forced them to become child soldiers and to undertake suicidal missions in order to further his own plans. Jack and Tia were the only orphans to survive these missions. He then proceeded to take control of Meteor G so he could take over the world by force, raining down deadly Noise upon those who would not subjugate themselves to him. After being betrayed by his subordinates and supposedly destroyed, King became an Energy Being and decided to wipe out the world using Meteor G figuring if he can't rule the world, he will destroy it.

The Archie Comic
  • Ra Moon in a sinister AI who crash-landed on Earth centuries ago with aspirations of control. Manipulating an ancient civilization into worshipping it—and even establishing bloody ritual sacrifice in its name— Ra Moon eventually tires of its slaves and decimates the entire civilization whilst sealing itself underground. Upon returning from dormancy in the present day and being found by Dr. Wily, Ra Moon placidly provides for Wily's conquests before betraying the doctor and revealing its intention to scour the planet of both humans and robots alike, unleashing a global EMP wave and causing worldwide catastrophe. Intending on powering up its wave to boil out the brains of any humans it hasn't already killed, Ra Moon's response to resistance is to turn Wily's own creation against him and order it to start maiming Dr. Wily before murdering him, and brainwashing every Robot Master that stands against it.

http://tvtropes.org/pmwiki/pmwiki.php/Monster/MegaMan