I won’t deny the impact that has had on the character’s depiction in the years since, including Ledger and Phoenix, but in this case it feels like an “over-representation” of the character, that he is and has always been this tragic figure trying to prove a point, rather than an elemental force of chaos that destroys because it amuses him. Besides, the Joker as portrayed by Phoenix is vastly different to the one in Killing Joke, where Arthur was always troubled and mentally disturbed even before he killed anyone, whereas in the graphic novel the character starts out as sane but massively depressed about life.