MCU: 10 Best New Villains Who Could Join Phase 4

8. The Brotherhood Of Mutants

There's actually an argument that suggests that the Brotherhood actually deserve their own movie in the same way Suicide Squad did. As long as it turned out to be better executed, anyway.

Even without their leader - who warrants his own appraisal here - the Brotherhood are a compelling group who could be introduced as a sort of terrorist group seeking to rise up against mutant oppression (which could easily be presented as a dirty secret of the government to explain their absence).

X-Men movies have already been heavily steeped in civil rights allegory and using the Brotherhood as a sort of militant protest group first would be a great way to have them clash with the existing Marvel heroes, as well as a means to introduce heroic X-Men.