LOS ANGELES - The buzz over Heath Ledger's performance as the Joker in The Dark Knight for the last few months is justified. With his final full film role, Ledger delivers what may be remembered as the finest performance of his career.

A press screening of the Batman Begins sequel last week had the audience cackling along with Ledger's Joker, a depraved creature utterly without conscience whom the late actor played with gleeful anarchy.

Ledger elevates Batman's No. 1 nemesis to a place that even Jack Nicholson did not take him in 1989's Batman.

Nicholson's Joker was campy and clever. Ledger's Joker is an all-out terror, definitely funny but with a lunatic moral mission to destroy all of Gotham, the city Batman (Christian Bale) thanklessly protects,

Spewing alternate personal histories for how he got the horrible scars on his face, the Joker hides behind distorted clown make-up that looks like a chalk drawing left out in the rain.

He masterminds a series of escalating abductions, assassination attempts, murders and bombings, all aimed at calling out Batman and proving to the tormented vigilante hero that they are two sides of the same coin.

'You complete me,' the Joker tells Batman, dementedly borrowing Tom Cruise's sappy romantic line from Jerry Maguire. Long before Ledger's death in January from an accidental prescription drug overdose, his collaborators on The Dark Knight had been describing his performance as a new high in the art of villainy for a comic-book adaptation.

Director Christopher Nolan, reuniting with Batman Begins star Bale, said Ledger came through with precisely what he had envisioned for this take on the Joker - 'a young, anarchic presence, somebody who is genuinely threatening'.

Bale added: 'It was as though they'd taken the Joker and all the colours, everything of it and just kind of put him through a Turkish prison for a decade or so. It's like he has gone through that personal hell to come out being this, if you can even call him mad, at the end here.'

A Best Actor Academy Award nominee for Brokeback Mountain, Ledger has earned fresh Oscar buzz for The Dark Knight, which could land him in the supporting-actor race.

'Some men just want to watch the world burn,' says Alfred (Michael Caine), Batman's butler, of the Joker.

Come July 18, when The Dark Knight lands in cinemas, the world will be watching Ledger burn up the screen.

AP