Though we guess he would have been a passable Morph?
Jackson was so eager to play the role that he tried to buy Marvel. He figured if he owned the company, who could say no? As if anyone in their right mind would say no to a squealing, dancing Professor X leading a team of ten-year-olds and a chimpanzee, which almost certainly would have been his first and final idea. The point is, Michael Jackson's X-Men would have been so transcendent that every time Professor X rose from his wheelchair to circle slide, so too would each handicapped person watching.
20th Century Fox
"Breaking news: Doctors stunned as millions of paraplegics worldwide have regained the ability to moonwalk."
Jackson's deal to buy Marvel obviously never went through, which is a mistake time travelers will hopefully repair, because he wasn't only looking to score the role of a super-persuasive man surrounded by magical children. He was also hoping to play Peter Parker, the Amazing Spider-Man.
It sounds vaguely ridiculous (in the best way), but he wasn't without his supporters. When asked about it, Stan Lee himself said that he thought Jackson would've been a great Spider-Man. How fantastic would that have been? Do you remember that scene in Spider-Man 3 where Tobey Maguire turned evil and delivered into our world cinema's worst dance number?