"The only reason I did that part was because they promised me the villain part in the following Batman, which they didn't do because Joel Schumacher — they fired him," said Coolio. "Me and him didn't get along that great anyway. ... The next Batman the villain was supposed to be the Scarecrow."

Schumacher told Heat Vision in 2015 that he courted Nicolas Cage for the part.

"After Forever's success, I wanted to do The Dark Knight. It was going to be very dark. I remember going to the set of Face/Off and asking Nic Cage to play the Scarecrow. The studio, and I'm not sure the audience, was in a frame of mind to go too dark with Batman at that time," said Schumacher.

The screenwriter on that lost project, Batman Unchained, also spoke to Heat Vision about his plans for the movie, which would have seen Scarecrow team up with Harley Quinn — the daughter of Jack Nicholson's Joker. Their villainous plot would have driven Batman insane and then committed to Arkham Asylum.

A hallucinating Batman would have had to confront all the villains from the previous movies in an all-star team-up. There would be cameos from Danny DeVito (The Penguin), Michelle Pfeiffer (Catwoman), Tommy Lee Jones (Two-Face) and Jim Carrey (The Riddler), all leading up to a final confrontation with Nicholson's Joker.

"Joel wanted to tie up all of the films. The Tim Burton films and his films, building up to this moment," said screenwriter Mark Protosevich.

But it was never to be. As a refresher, here's Coolio's much smaller role in Batman & Robin.