Why not wait til joker movie is out

Obviously Heath Ledger, he brought the Joker alive and showed how mad and psychotic he was.

I like the Jack Nicholson the best because instead like a heath ledger joker he was a comic joke

Heath Ledger is the obvious choice. He is nothing short of the most accurate depiction of the modern day joker. Everything from the personality the suit he's sportin'.

Not rating him as the best but Cameron Monaghan is definitely over looked for his performance

When has he played the joker?

Gotham the tv show

I would’ve chose Mark Hamil but I didn’t see him as an option, in my opinion Mark is the Joker; no one can compare to that amazing psychotic laugh. But live action wise, I’d have to pick Heath Ledger. He was just so spot on to the anarchy styled joker, and the things his character did showed just how psychotic the Joker is. His performance is an awe inspiring master piece that will continue to live on through the decades as one of thee best live action performances of the clown prince of crime.

In the Gotham series, he was never named dropped as "The Joker" bit it was his role

Iedger was absolutely fantastic ofc, but monaghan is so underrated!!! he pulls off not one, but TWO separate performances of joker/proto-joker and has sent multiple chills down my spine throughout the series! he did a wonderful job but ledger's was obviously very much more influential in the development of the joker character as a whole.