What if Jack Nicholson played the Joker on the Adam West TV series?
I don't know how big of a star he was when the Batman TV series first went on the air in 1966. I can't help but think about what a "young" version would've been like as the Joker. His first real movie was in the original Little Shop of Horrors from 1960. He plays this masochistic dental patient (Nicholson was pretty much playing the role that Bill Murray would play in the 1986 version), and he is admittedly very creepy in the role. It makes you wonder if Jack Nicholson was sort of destined to often play unhinged, eccentric people.
https://www.youtube.com/watch?v=RAli9a8bbys
https://www.youtube.com/watch?v=LPQSiTIb2Ac&t=1s