When you hear the name Tom Cruise, what descriptions spring to mind?

Fervent Scientologist?

Self-proclaimed psychotherapy expert? (Easy, Matt Lauer, easy.)

Oprah couch-jumper?

Wait, doesn't the guy act or something, too? That is sometimes hard to remember, what with the others taking up all the headlines. To say that Cruise, once (maybe still, who knows) the world's most popular actor, has hit a rough patch the past couple of years is an understatement.

But that might be changing. (Mild spoiler alert follows.)

In "Tropic Thunder," Ben Stiller's poke in the eye of Hollywood filmmaking and its spoiled, self-absorbed practitioners, Cruise plays Les Grossman, a gleefully profane studio executive who sees everything — life and death included — in terms of profit.

And boy, can he dance.

It seems sort of silly to call such a hilarious performance — and it really is hilarious, just laugh-out-loud, the best thing about a pretty decent movie — "brave." It's not like he did it for free, or risked some sort of personal danger to shoot it.

But Cruise is nearly unrecognizable, wearing a fat suit, a bald wig and what one hopes is a fake forest of fur on his arms and chest. In a town where appearance, especially for such a good-looking guy, is so important, it's safe to say we can at least call the role "risky."

The risk is paying off. Cruise is getting universally good notices for the role, good enough that there's talk of it lifting him out of the tabloid trap he's found himself in lately. Can one role do that?

Ask John Travolta. When he appeared in "Pulp Fiction" in 1994, Travolta's career was slumping. "Urban Cowboy," his last decent credit, was already 14 years in the past. (We will not, for the purposes of this argument, consider "Look Who's Talking" and "Look Who's Talking Too.")

But Quentin Tarantino saw something no one else had seen for years, cast Travolta as gangster Vincent Vega (another great dancer) and the next thing you know, "played Vinnie Barbarino" was no longer the description most likely to be used in the first sentence of stories about the actor.

The secret in both cases: Cruise and Travolta were willing to go beyond the audience's expectations. Cruise had to be willing to look and act absurd. Travolta didn't have to go that far, but did have to play a cold-blooded killer who suffers a final indignity — shot to death while sitting on the toilet.

In the case of Robert Downey Jr., Cruise's "Tropic Thunder" co-star, no one questioned that he was a great actor. His personal life left a little to be desired — OK, a lot — but he seemed dependable enough playing quirky roles in nice little movies such as "Kiss Kiss Bang Bang."

Then came "Iron Man" in which the casting of Downey seemed a curious choice. Yet he channeled his innate quirkiness into the role of a superhero and proved that he could open a blockbuster. Now, in "Tropic Thunder," he takes the next step, risking all sorts of backlash by basically playing a character in medically aided blackface — and he is again reaping the rewards of taking that risk.

But nothing lasts forever. Cruise's Oscar-nominated performance in "Magnolia" spurred a re-evaluation of his acting abilities, and then all that couch-jumping and whatnot derailed him to the point that he needs a role like Grossman to boost himself again. Post-"Pulp Fiction," Travolta cruised along there for a while, making good films like "Get Shorty" and "Primary Colors." Then, two words: "Battlefield Earth." Accumulated good will screeches to a halt.

So what happens? Decked out in a dress and a fat suit, Travolta plays Edna Turnblad in the remake of "Hairspray," a role originated by Divine, the transvestite. And suddenly he's a hot property again.

The moral? Take chances. Go for broke. Don't be afraid to make fun of yourself.

And someone get Jim Carrey in a fat suit, fast.

Read Bill Goodykoontz's blog at http://www.goodyblog.azcentral.com.