Being beautiful isn't all it's cracked up to be. Sometimes you want to be respected for your brains and talent.

Just ask Brad Pitt.

Audiences will find this cinema heartthrob in full silly mode in the Coen brothers' spy spoof "Burn After Reading."

He's been cultivating silliness for a long time.

Almost from the weekend in 1991 when moviegoers flocked to the opening of "Thelma & Louise" and laid eyes on Pitt as a young, charming, impossibly sexy cowpoke, this Springfield, Mo., native and former University of Missouri student was marked as the guy women want to look at and guys want to be.

Pitt has been smart enough to run with that, to make sure that every once in a while he shows up on screen as a sexy hunk. Roles like that are his money in the bank.

But I can't think of another movie sex symbol — male or female — who has worked as doggedly to defy that label at every opportunity.

Almost immediately after hitting it big, Pitt began toying with his image.

For his 1992 "A River Runs Through It" director Robert Redford capitalized on Pitt's charm, casting him as a self-destructive small-town rogue. But in his next film, the crime thriller "Kalifornia," Pitt hid behind a skuzzy beard and shaggy mane. And the next time we saw him, in the Quentin Tarantino-penned "True Romance," he was even hairier in a brief performance as an emaciated drug freak. Not only was it a comic role, but the pretty dude of "Thelma & Louise" was all but unrecognizable.

In fact, Pitt has devoted much of his career to hiding behind characters that are the antithesis of the pretty boy.

He'll grow hair. He'll shave it off. He'll whip it into absurd pompadours.

He'll adopt impenetrable accents (like the Irish gypsy pugilist he played so memorably in Guy Ritchie's "Snatch").

He'll portray medium-sized roles in big ensemble productions ("Babel," the "Ocean's" series) and knows how to exert just enough star power to make his characters memorable without capsizing the boat.

He's not afraid to play neurotic or scary. If you haven't seen him as Jesse James in "The Assassination of Jesse James by the Coward Robert Ford," go rent the DVD. Yeah, he oozes the James charisma ... but he's also certifiably mad, a paranoiac around whom no one is safe.

For every good-looking leading man gig he accepts ("Mr. & Mrs. Smith"), Pitt offers two or three unusual, unexpected performances. Sometimes he even combines the two, as in "Fight Club," where he played Edward Norton's sexually charged, anti-establishment feather-boa-wearing alter ego.

And in "The Curious Case of Benjamin Button," out Dec. 25, we'll see him as a man who is born as an aged adult and gradually gets younger.

Most of all, he likes playing goofy. I'd put Pitt on the short list of our best comic actors. He's not afraid to look ridiculous ... in fact he courts it.

In "Burn After Reading" we get Pitt in full funnyman mode as Chad Feldheimer, a trainer at Hardbodies Gym. Chad obtains a computer disc filled with useless information and becomes convinced it's a treasure trove of spy stuff that he can sell to the highest bidder.

Chad likes to think he's sharp, but his cocky pose is as phony as the blond highlights in his hair.

He's at his most natural when doing a little funky dance of celebration to the music playing in his head (or on his iPod). He's an infant in a tight shirt, a gum-chomping boob who might be narcissistic if he had any self-awareness at all.

When he tries to be mysterious and/or menacing, he's so transparent that nobody takes him seriously.

But Brad Pitt the comic actor? We can take him very seriously.