Don Cheadle would prefer it if people didn't take him so seriously. The Kansas City, Mo., native has played everything from a gold-toothed gangster (1995's Devil in a Blue Dress) to a chilled-out angel (2000's The Family Man), and still Hollywood has managed to find a pigeonhole for him: the actor's actor. ''I heard somebody say they were in a room and [someone else] said, 'This script is kind of silly — we wouldn't want to give this to Don Cheadle,''' grouses the Oscar nominee over half-eaten room service in a midtown Manhattan hotel suite. '''We don't want to embarrass him.'''

A wide, bright smile breaks across Cheadle's face. ''What are you talking about?'' he blurts. ''I played Buck Swope. I'll tell you if I'm silly enough.''

Okay, so we'll give him Swope, the porn star cowpoke from 1997's Boogie Nights. And Basher Tarr, the Cockney crook from Ocean's Eleven and its two sequels. But Cheadle, 42, is best known for his courageous hotel manager in Hotel Rwanda, a very serious role indeed, for which he earned a Best Actor Oscar nod. After that, he coauthored Not on Our Watch: The Mission to End Genocide in Darfur and Beyond, a very serious book aimed at inspiring activism against atrocities in war-torn Sudan. Is it any wonder filmmakers have trouble envisioning Cheadle doing spit-takes and pratfalls?

His latest part, though, as a real-life ex-con-turned-radio and TV host in July 13's Talk to Me, shows off Cheadle's comic agility without sacrificing his thespian rep. The character of Ralph Waldo ''Petey'' Greene (who died in 1984) is an actor's dream: tortured and misunderstood. And as a source of yuks, his foulmouthed, un-PC wit makes George Jefferson look like Thomas Jefferson. ''Have you seen Petey Greene's 'How to Eat Watermelon' on YouTube?'' Cheadle asks. He cracks up while describing the race-baiting segment from Greene's successful TV show. ''It's brilliant, the level of social commentary and stereotyping. You find yourself laughing, then going, 'Why am I laughing? Should I laugh at that?'''

In the film, Greene smack-talks his way onto a D.C. radio station where — despite becoming an on-air sensation and a community hero — the heavy-drinking philanderer wrestles with the station's uptight program director (Kinky Boots' Chiwetel Ejiofor), along with his own self-destructive tendencies. Director Kasi Lemmons (Eve's Bayou) knew Cheadle was a cinch to capture the humor and pathos. ''I've known Don for a long time,'' she says, ''so I knew he'd be outrageous, but I also thought that he was going to fly.''

Though Cheadle jokes about selling out and wanting to do a ''big, dumb comedy,'' the Crash star isn't breaking his neck to become the next Will Ferrell. ''I didn't work between Ocean's Twelve and Reign Over Me — that's a year and a half,'' says Cheadle, who lives in L.A. with actress Bridgid Coulter (Rosewood), 38, and their two daughters, 12 and 10. ''I could just take something, but I waited until my business manager called up like, 'Okay, you need to work.''' But Cheadle — who's been a working actor for more than 20 years, putting in unceremonious appearances on TV (Fame) and in film (The Meteor Man) — isn't just waiting for great roles. He recently tried to marshal an adaptation of Elmore Leonard's Tishomingo Blues into production but couldn't muster the funding — a hurdle that nearly silenced Talk to Me. He hopes that the success of modestly budgeted films like Crash and Little Miss Sunshine will result in more cash for projects like the unorthodox Miles Davis biopic, which he intends to star in and possibly direct. ''I want to start off the movie by saying 'Some of this s--- might've happened,''' he says, nailing Davis' bluesy rasp. ''Because that's how he was.''

In the meantime, Cheadle remains invested in another project. Since becoming aware of the violence in Darfur while filming Hotel Rwanda in South Africa, he has testified before the Senate, met with Condoleezza Rice, and teamed up with Ocean's cronies George Clooney, Brad Pitt, and Matt Damon in the cause, with several Ocean's Thirteen premieres doubling as benefits. ''Trying to juggle being a dad, an actor, a husband with all of that, it's tricky,'' Cheadle says. ''But it's hard to say, 'Eh, I don't have any time for it.' Especially once you've been there. Once you interact with people and realize that's you. You don't speak the same language, you don't eat the same food, but that's you.''

Normally easygoing, the guy grows positively fierce now, criticizing our government for imposing sanctions without collaborating with the U.N. ''It's how our country likes to do things under this leadership,'' he says, frowning. ''[The U.S. decides] 'We'll do it.' No, you can't do it, idiot! We [as a world community] have to do it. We have to say...these things affect everybody.'' Suddenly, it's impossible not to take Don Cheadle seriously.