When it comes to the best supporting actor Oscar, the winning hand could be held by The Joker.

That, of course, is the late Heath Ledger, whose eye-popping turn as The Joker in “The Dark Knight” set a new standard for comic-book villains. Practically before the end credits rolled, Ledger, who died in January 2008, was being touted as a shoo-in for this award. And his posthumous win at the Golden Globes last month would seem to boost his odds.

But his four competitors are also highly deserving, leaving at least some room for surprise when the awards are announced Sunday:

ACTOR: Josh Brolin
MOVIE: “Milk”

THE DEAL: Brolin is unnerving as a killer-in-the-making in this biopic of the gay politician Harvey Milk. One theory: The academy may give him the statue after overlooking his major role in last year’s multiple-award winner “No Country for Old Men.”

ACTOR: Robert Downey Jr.
MOVIE: “Tropic Thunder”

THE DEAL: A surprising nominee, since the movie was a crude summer comedy and Downey was playing an Australian actor who darkens his pigment to play a black role. Downey was excruciatingly funny, but expect a chorus of gasps if he wins.

ACTOR: Philip Seymour Hoffman
MOVIE: “Doubt”

THE DEAL: As a priest who may or may not be a child molester, Hoffman turns in one of his typically restrained, pitch-perfect performances. If anything, Hoffman’s bar has been set so high (he won best actor for 2005’s “Capote”) that this smallish role may not clear it.

ACTOR: Michael Shannon
MOVIE: “Revolutionary Road”

THE DEAL: As a mentally ill young man with crystal-clear insight, the little-known Shannon clearly made an impression on Oscar voters. More so, in fact, than his major co-stars, Leonardo DiCaprio and Kate Winslet, neither of whom earned nominations for this film.

ACTOR: Heath Ledger
MOVIE: “The Dark Knight”

THE DEAL: Sentimentality aside, Ledger seems to tower above his fellow competitors. One issue already being raised: Who will accept on his behalf?