Magneto (Ultimate Marvel)

Magneto has long been seen as the main antagonist of the X-Men mythos yet his Ultimate Marvel counterpart took this to a new level - unlike the more antihero Magneto most X-Men fans know from the "mainstream" series the Ultimate version of Magneto was dark, cynical and sought to utterly dominate humanity (who he refered to as "insects") - he also openly called for genocide on more than one occassion.

The X-Men movie mythology borrowed heavily from the Ultimate comics rather than the "mainstream" and thus the movie version of Magneto can be seen as having a lot of the personality traits of the Ultimate Magneto (which explains why he was willing to commit mass genocide in that film, seemingly in contrast with what most X-Men fans believe to be Magneto's character).