The X-Men have faced a few telepathic threats over the years, though the majority they've come across (whether it's Emma Frost, Jean Grey, or Psylocke) normally end up fighting on their side. However, one who most definitely had no interest in working with them is the Shadow King, a villain who exists on the psychic plane and has made a point of making any number of X-Men his pawns over the years. His desires are simple; Shadow King wants to conquer and destroy the world, and as so few characters can confront him on the psychic plane, he's come close to doing so on many occasions. He is in fact so strong that a confrontation with Professor X in that realm actually ended with him putting the then healed leader of the X-Men back in a wheelchair in the real world, so he's clearly not someone to be messed with.
