If the theory of multiverse holds any water, there are other worlds out there in which Tim Curry played the Joker, where George Miller's Justice League Mortal wasn't killed by weird Australian laws and where Tim Burton made Batman Forever and nobody hates Joel Schumacher. Possibly.
Over the years, there have been a massive number of cancelled plans for Batman movies. Seemingly hundreds of actors were almost cast as the Caped Crusader himself or as members of his entourage or his rogues' gallery. More than 20 movie projects were in production in some form. Countless scenes that were planned and cut at some point. Basically, Batman movie history could have been very different.
Now, some of those changes might have improved Batman for us all, but some were definitely better left unrealised. They were just too strange to exist in this world or any other, and they prove, without question, that sometimes it pays to have a filter between the brains of executives, writers, directors and the screen.
And if you think Jared Leto's Juggalo pimp Joker was weird, you ain't seen nothing yet...