
IGN gives its reasons for choosing Magneto as being:
"Magneto has become bigger than his peers and virtually all of his enemies. It's the sign of a great character when his presence dominates a story and his absence creates a vacuum that cannot be filled by any other. Through his legendary role in Marvel Comics over the years as well as fantastic portrayals in film and animation, it's hard to argue that there has ever been a villain more complex, nuanced, sympathetic and yet irrevocably evil."