Magneto (X-Men)

"I've been at the mercy of men just following orders. Never again." (X-Men: First Class)

Magneto is considered the main antagonist of the X-Men series. He was the first foe that the X-Men ever faced, debuting in X-Men #1 in 1963. Known as "The Master of Magnetism," Magneto uses his immense power over metal to fight against the oppression faced by his mutant brethren. He feels so passionately about this cause due to the fact that, coupled with being a mutant, Magneto also saw and experienced the Holocaust firsthand, and has seen kind of hatred and atrocities of which mankind is capable.

Sympathetic villains are amongst some of the most popular villains ever conceived, and Magneto reigns supreme among them. While his goal is sometimes as extreme as genocide towards humanity, Magneto has always been backed by thousands of fans insisting "Magneto was right," fans who are exactly the people that Magneto would want to see killed. And even those who don't agree with Magneto's viewpoint can usually say that they understand it. He has seen his own people killed by those who were too prejudiced and scared to look past their orders, and doesn't want to see this replicated against mutants, a group that already experiences discrimination and social tension at the best of times. While he himself has gone back and forth on which side he supports, he will always support his brethren, a choice which anyone can respect, even if they don't agree with his methods.