As the amoral, drug- and sex-addled right-hand man in "The Wolf of Wall Street," Jonah Hill wore a set of gleaming false teeth. They were based on the look of the trader who helped inspire his character, but they made him talk funny.

"I had a horrible lisp, once I put the teeth in," he said. So on the advice of a dialect coach, he practiced talking with them in for several hours a day, calling unsuspecting customer-service representatives to shoot the breeze. "I would keep them on the phone for like two hours," he said, "just asking about all the different appliances."

Staying in character requires commitment. Among this year's crop of supporting actor Oscar hopefuls, Jake Gyllenhaal, for his role as a police detective hunting for missing children in "Prisoners," covered his body with temporary tattoos. In the blue-collar drama "Out of the Furnace," Casey Affleck got bruised in bare-knuckle boxing sessions.

Bradley Cooper endured an unfortunate, but period-appropriate, perm in "American Hustle." And Jared Leto lost more than 30 pounds and shaved off his eyebrows, among other make-unders, to play a transgender AIDS patient in "Dallas Buyers Club."

Leading men in Oscar-bound films are often called upon to metamorphose, most often from hunkiness to debilitation, chiseled hero to lout (and back again). But actors in roles with sparser screen time may do even more, transforming themselves physically and walking off with their scenes with portrayals of depravity or verbal dexterity. (Christoph Waltz in "Inglourious Basterds" and "Django Unchained" had both.) The emotional turns, in shorter sequences, become more harrowing: Christian Bale embodied both the spirit and the failure of "The Fighter" in just one scene. And bad haircuts are surprisingly effective for prizewinners: Witness Javier Bardem's shaggy pageboy in "No Country for Old Men."

This Oscar season, supporting actor hopefuls are making all the usual moves, transforming bodily and emoting greedily, along with some unexpected shifts. There are comedians doing understated drama (and vice versa, as in James Gandolfini's turn in the romantic comedy "Enough Said") and foreign-born actors diving into American films in a major way.

And at least one front-runner, Michael Fassbender, has publicly eschewed award campaigning for his performance as the sadistic plantation owner in "12 Years a Slave."

Most pundits see Leto and Fassbender as the leaders in the supporting actor race; both have earned precursor awards, from industry groups and critics, and are part of films with widespread trophy momentum. But the category is often ripe for surprises.

Surging ahead are Daniel Bruhl, a Spanish-born German actor playing Formula One driver Niki Lauda in "Rush," and Barkhad Abdi, a Somali actor from Minneapolis making his feature debut, opposite Tom Hanks, in "Captain Phillips." Both Bruhl and Abdi have gotten nominations from Golden Globes voters and the Screen Actors Guild, whose membership overlaps with the Academy's. The Golden Globes winners will be announced tonight, and the Oscar nominees next Thursday.

For Leto, "Dallas Buyers Club" is a showy return to acting after five years of focusing on his band, Thirty Seconds to Mars.

"For a few years, the scripts were still coming, but after that, people get the point," he said.

But when "Dallas Buyers Club," starring Matthew McConaughey as the real-life AIDS patient and experimental treatment crusader Ron Woodroof, came his way, he was ready. He auditioned for director Jean-Marc Vallee over Skype, before a gig in Berlin, playing the character, Rayon, even then.

"I had a little pink sweater on and pulled that over my shoulder, and I proceeded to flirt with him for the next 20 minutes," Leto said. "And woke up the next day with the offer."

He stayed in character for the 25-day shoot.

"Every morning, no matter what, I stepped out of that passenger van when I got dropped off on set, and I was wearing my heels," he said.

Although he gained the weight back, leaving Rayon behind wasn't easy.

"She's funny and fun and full of grace and wit," Leto said.

For different reasons, Will Forte is not at all eager to move past his role in Alexander Payne's black-and-white "Nebraska," relishing the accolades he's earning for playing against type.

"I am not used to getting awards," he said at the National Board of Review gala on Tuesday, where he picked up a prize for his performance as a wayward son on a road trip with his father.

Forte, a former cast member of "Saturday Night Live," said he never expected to be in a film by an Oscar winner like Payne, and he was petrified that the cast, including veterans like Bruce Dern, had acting secrets that he did not.

"When you watch this movie, you're watching somebody who's in the process of being taught by a legendary actor and an amazing director," he said in a recent interview.