Who is the greatest of the worst, villainous, bad guys? My younger brother and I put together 16 of what we believe are the top villains of the X-men. Magneto all the way...he's one of those villains that you could actually relate to. He's politically, emotionally, righteously (in his mind) fighting for mutants; for their rights and place on earth. And at some point you have to feel some amount of sympathy for him. For humanity and all its "righteous" leaders created the man Magneto is today...they treated him with violence and his only defense is too retaliate the only way he knows how. Sinister would be a close second, just because he freaks me right the hell out!