Live Action Series Joker: Campy, not really Psycho, just a clown gone bad
Comic Book Joker: Possibly The Greatest, Most Sinister, Malevolent, villian in comic book history. Does everything in his power just to get Batman to smile. In addition, he tests the code of the hero; Regardless of what the villian does I will not kill him. Death is the only way to stop the Joker, and he knows Bats will never do it.
'89 Joker: Jack Nicholson the embodiment of the Joker, just look at his eyes. Come on: Winged freak... Terrorizes? Wait'll they get a load of ME
Since '89, no one could or would try to attempt to play the Joker because of high precedent set by the first Joker. When Batman Begins ended, you are left with the question, Who can hope to attempt this? Because that brave soul can only hope to match Nicholson's performance or create his own Joker; topping it is out of the question. Heath Ledger does not strike as the, Crazy I'm ready to kill type. (Personally I think they should bring in Hugo E Blick, Young Jack Napier in Batman '89)