If they reboot Batman and cast a new Joker...
Tom Hiddleston would be absolutely PERFECT for the role. Yes Tom Hiddleston, the guy who played Loki.
The guy has everything that would make a modern classic version of the Joker:
The grin? Check
The skinny build? Check
The long face? Check
The classy swag? Check
and most importantly the ACTING ABILITY? CHECK.
WB needs to make this happen