Imagine the movie The Dark Knight if Heath Ledger hadn't died. What would critics say?
Would they say Dark Knight is a masterpiece of crime noir? I doubt it.
Would they wonder to what well of darkness Heath Ledger descended to find this character? Not likely.
They'd say it is yet another comic book movie in a long series of disappointing comic book movies. Ledger's Joker, though different that Nicholson's, was in no way superior, and in some ways inferior. He lacked depth. He was, in fact, single dimensional. Unlike Nicholson's Joker, Ledger's Joker had not one redeeming quality. He was, quite simply, an agent of chaos, and while good for the special effects department, he existed as nothing but a foil for Batman and the police. No matter how chaotic and evil, under no other circumstances save the actor's untimely death is such a portrayal praised.
No, if Heath Ledger hadn't died, critics might have pointed out that Gary Oldman's vastly understated role as Commissioner Gordon was, in fact, the best played role in a movie chock full of lifeless, one dimensional characters. They might wonder what Michael Caine won't do for money. They might say Morgan Freeman should have known better than to involve himself with this project.
But no, Heath Ledger died. Tragically. Too soon. And because he died, critics praised his portrayal of the Joker. They placed Dark Knight on their ten best movies of 2008 lists, all because Heath Ledger died a tragic and pointless death. It makes for a good story, kinda like how Bon Scott died the night after he recorded Highway to Hell. Ohhh, he delved too deep into the heart of evil.
And the witches in Macbeth sometimes really conjure evil spirits. And all the actors who play Jesus die. Blah blah blah whatever.
I think time will ultimately place Dark Knight right alongside the previous incarnations of the man in the bat suit, right where it belongs. Maybe not so pathetic as the previous incarnations, but certainly no better than its better predecessors. Tim Burton knew what he was doing when he camped out the Batman series, for it is high camp, and when taken too seriously it makes a mockery of itself.
It is a shame Heath Ledger died. But that is all it is. But if you really want to know where he found his Joker, he was in the marketing department of the movie studio where he worked.