Meg Ryan is cute and sugary. "X-Men" star Hugh Jackman (search) is a tough guy with his Wolverine (search) claws. "Dawson's Creek" Katie Holmes is the girl next door.

In Hollywood, typecasting is as common as plastic surgery — but a star's image usually is much harder to shed than a few wrinkles around the eyes.

That doesn't stop actors from trying to make over their on-screen personas. Just this month, several celebs have taken on roles that push the envelope.

In her new thriller "In the Cut," Ryan scraps her sweetheart image to play a sexy writing professor. Jackman is singing and dancing as a gay man in Broadway's "The Boy From Oz." And Holmes has gone from a good-girl TV teen to a rebellious, punked-out character in "Pieces of April."

As much as diversity can be great for an actor's resume, some film insiders say it's tough to convince the public to buy into a star's new identity.

"It's really impossible, generally because your image becomes your brand name," said E! Online movie columnist Anderson Jones. "I think what Meg Ryan (search) has found out is that people aren't really interested in her unless she's playing a daffy, goofy, in-love kind of woman."

The transition can be smoother for less well-known actors like Holmes than for seasoned stars, according to New York Post movie critic Lou Lumenick.

"It's harder for an older actress because [Ryan] established this persona over a number of popular films," he said. "It's easier for [Holmes] because movie audiences don't really have an image of her."

Ryan, for her part, denies that she was deliberately trying to break out of the apple-pie mold by taking on a more dramatic part.

"You all can say what you want," she told Lumenick for his Post review. "I've done 30 movies and I've done seven romantic comedies. So I don't know what the typical Meg Ryan movie is."

But her public does. Think: "When Harry Met Sally"; "Sleepless in Seattle"; "You've Got Mail."

It's possible fans won't follow stars from one role to another. In Jackman's case, he's minimized the risk of putting off fans by experimenting on the stage rather than on the big screen.

Still, despite audience's wariness to accept their favorite actors in a new light, Lumenick said major changes can be the best way to break out of the mold. 

"You go for a drastically different kind of role," said Lumenick. "You go from warm and cuddly roles to playing psychopathic killers."

Robin Williams, for instance, was successful when he went from playing the funnyman to a psychopath in "Insomnia" and "One Hour Photo." Dustin Hoffman went from the hapless college grad Benjamin Braddok in "The Graduate" to a gritty role in "Midnight Cowboy."

"What celebrities have to do if they are trying to change their image is to not reek of desperation," said Jones, who pointed to Jim Carrey as an example of a less successful switch from goofball comedian to serious actor.

"It hasn't worked for Jim Carrey," he said. "You hope that your career looks like it's grown naturally and not that you were so desperate for work that you started doing dramas so people would take you seriously."

In other cases, stars try to shed a reputation they've gotten because of their off-screen behavior.

Rebel Aussie Russell Crowe is spending more time shopping for baby clothes with his expectant wife than getting into brawls and having high-profile love affairs with co-stars.

Even Britney Spears, who went from good girl to bad girl practically overnight, has reportedly been talking about putting her clothes back on. In a recent issue of Newsweek, she said she had some regrets over the Esquire cover photo in which she appeared wearing nothing but high heels and a white sweater.

"I did feel kind of weird after those photos," Spears told Newsweek. "I learned my lesson and you won't see me like that for a while."

Some fans say it's easier to accept changes in actors' real-life roles than in their on-screen ones.

"I think that's probably easier to overcome than roles in films in terms of how we perceive people," said movie buff Cristina Barden of Long Island, N.Y. "You get some good PR and the last thing in people's minds is what came before. We have cultural amnesia."

Lumenick said the key is to go underground for a while. After getting into fistfights and having a very public affair with then-married Meg Ryan, Crowe all but disappeared.

"What he did after that debacle was basically kept a low profile the last two years," Lumenick said. "That's probably an approach that would help."