Spoilers in 2nd paragraph
Arkham Joker as voiced by Mark Hamill. Love all the BTAS work but the character design in the games is to die for. Some of the best Joker moments ever. Helps that they had Paul Dini writing it. There’s no way the games would have been as amazing if they hadn’t brought him in.
Spoilers below
Arkham city is one of his best deaths ever. The fact that it happened in the Monarch Theatre and Batman had to carry him out like some kind of Cain and Abel story was poetry that could only have been dreamt up by Dini.