Mutants make a big song and dance about humanity being the ones who will one day wipe them out, but they're actually their own worst enemies. Sure, the X-Men comics feature plenty of villainous homo sapiens going after the superiors – the U-Men, Sentinel creator Boliver Trask, the God Loves, Man Kills Guy – but they're still just humans.
Humans can only do so much damage to a species which includes people with optic blasts, phenomenal physic powers, and healing factors which essentially mean they can never die. In that case, some of the most formidable enemies the X-Men have encountered over the years are fellow mutants or super-powered people.
And they've made a considerable amount of said enemies over the years. Whilst the mutant minority allegory often gets played up with the intolerant, protesting humans and politicians, the large majority of X-Men stories see them pitched against bad guys who are on a level playing field, powers-wise. Sometimes, they even have an advantage.
What with fiery space gods who can destroy entire planets in seconds, ancient mutants who can reconfigure themselves into other shapes and have apparently limitless power, and alien races that infect and destroy everything they come across, you have to wonder where the humans even figure in.
Here are the actual twenty most powerful X-Men villains of all time.