Grodus:

Grodus, machine or martian? No one knows about this strange leader of the X-Nauts. He could be an alien in disguise. Or a super-computer built by someone unknown. Either way, Grodus did the unthinkable: HE was the one who kidnapped Peach recently to try and steal some stupid magic map or something, and only Bowser can do that! That makes him the newest enemies of the Koopa's! ....After Mario of course.