Onslaught

Lastly, Onslaught is an uber-powerful antagonist who basically possesses the powers of both Professor X and Magneto. Additional abilities include manipulation of matter, a certain degree of omniscience, immense strength that would make the Hulk cower in fear, and others.

His telepathic ability would make him interesting and unique in the MCU. Scarlet Witch is the only character who’s used this ability, and then only to a small degree in Age of Ultron. Maybe Marvel should consider having its heroes face off with antagonists who have unique skills and abilities.

Of course, this won't happen anytime soon, since Fox owns the rights to Onslaught.