The Joker is easily one of the best villains in film and TV (and obviously, comic book) history, but who is the best Joker? Jack Nicholson combined the mischievous campiness of the character with the deranged thirst for violence. Heath Ledger’s The Dark Knight Joker was somehow just as iconic as Nicholson's and fitted Christopher Nolan’s Gotham perfectly. And Mark Hamill has basically become the standard-bearer of the Joker through his work in the animated Batman series.
We haven’t seen Jared Leto’s version on the big screen yet, so we can’t consider him, but that’s still a helluva lineup for Jokers, not to mention the original Joker, Cesar Romero, providing a template for the others to follow (or not). So maybe instead of arguing who was the best Joker in film and TV history, we should argue that the Joker has been portrayed the best out of any superhero or villain in film and TV history.