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

Mega Man Zero

  • Dr. Weil is notable in being one of the most evil beings in the Mega Man series despite only appearing in a few games. 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 king’s 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 Pat’s 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. He’s eventually defeated, but his manipulations of Pat and Geo convince the latter to abandon everyone in his life for a time. He’s 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 he’s 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 Force’s 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.

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.

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