8. Professor X In A New Body - X-Men: The Last Stand
In X-Men: The Last Stand, Professor Charles Xavier was brutally killed when Jean Grey used her massive telekinetic powers in her Phoenix guise to turn him to dust when he was trying to help her. He didn't re-emerge until the post-credits scene of that same movie when Dr. Moira MacTaggert checked on a comatose patient who greeted her with his unmistakeable voice, leaving her shocked. This scene made audiences believe Professor Xavier would be living in a new body from that point onwards but, as of X-Men: Days Of Future Past, the whole movie was essentially retconned and it was as if the X-Men's founder had never been killed in the first place.
