The most famous of these unmade movies is Spider-Man that would have been written and directed by James Cameron (Aliens, Avatar). James Cameron’s Spider-Man would have been released sometime after his smash Terminator 2 (1991) and would have featured Spider-Man battling Sandman and Electro. Unfortunately, the company that owned the film rights to the webhead went bankrupt and legal issues with the character would only be settled in the early ’00s.
For a time Cameron was also attached to produce a The X-Men movie in the 1990s too.