For the longest of times, Jack Nicholson's interpretation of The Joker was considered to be the definitive one in popular character. 

Of course then Heath Ledger came along in 2008 with The Dark Knight to launch endless Nicholson v Ledger Joker debates the world over. Did you know that we almost lived in a universe where we would be having Lithgow v Ledger debates instead?

That's right, John Lithgow was Tim Burton's first choice to play The Joker. And it's easy to see why. Lithgow bringing his trademark charisma to a villain like The Joker would have been amazing to see. 

Unfortunately for Lithgow he spent the majority of his audition trying to convince Burton that he wasn't right for the part. Something he still regrets to this day. 

"My worst audition was for Tim Burton for Batman,” Lithgow told Vulture at the Tony Awards. “I have never told anyone this story, but I tried to persuade him I was not right for the part, and I succeeded. I didn’t realize it was such a big deal. About a week later I heard they were going after Robin Williams and Jack Nicholson.”

It wasn't that Lithgow had anything against Batman or The Joker, he just felt at the time that he didn't have the energy for it after coming off Broadway. 

“I was doing M. Butterfly on Broadway and it was an exhausting show. It would have meant leaving that show and going right into a movie, and I said, ‘I just don’t think I can’. How about that for stupid? Actors are not necessarily smart people.”

Via Vulture