By Ashley Williams

LOS ANGELES, Calif. --

No pain, no gain – this cliché is especially true for actors suiting up as on-screen superheroes.

Many stars have gone the extra mile to fully commit to their character. They’ve hit the gym and packed on the pounds in order to take on the persona of their on-screen superhero. Just like many of their superhero alter egos, these stars alter their bodies and go from boy next door to a buff & bulked up leading man – but it doesn’t come without hard work. Whether they’re shedding pounds, toning up or gaining muscle, AccessHollywood.com counts down the Top 10 stars that have undergone massive body transformations for their super-powered roles!

10. Ron Perlman in “Hellboy” (2004)
Ron Perlman transformed himself into the defender against the forces of darkness in “Hellboy,” showing off his robust body in his red-skinned costume. He’s always been a built guy, but he altered his looks from muscular “boy” in 1997’s “Alien: Resurrection,” to muscular “man.” This always-looking-for-a-fight superhero focused on bulking up his upper body muscle; his lack of shirt in the film proves he’s not afraid to bear it all. He did it again in 2008 for “Hellboy 2.”

9. Thomas Jane in “The Punisher” (2004)
Thomas Jane sought out his revenge in “The Punisher” — and he did well to live up to the strength and sturdiness of the character based on the Marvel comic book. He showed off his physique while sporting a skull logo across his muscular chest. The very good-looking actor has always sported a nice physique but he began flaunting a more muscular build following his 1999 role in the cult classic “Deep Blue Sea.” With his weapons in hand and his bulging biceps, he showed no mercy on his victims.

8. Seth Rogen in “The Green Hornet” (2011)
He’s green and he’s lean. Seth is always the first to make us laugh, but Seth’s fit new physique he showed off in “The Green Hornet” was no laughing matter. The Canadian actor and “Knocked Up” star changed his chubby image and sported a slimmer physique for the title role. Seth now flaunts a more slender athletic build and a more confident self, but is still making us all laugh.

7. Tobey Maguire in “Spiderman” (2002)
Tobey Maguire changed his boy next-door look to muscular superhero in the “Spiderman” films, buffing up for the role and using his spider-like abilities to fight evil. He went from lanky nerd in 1998’s “Pleasantville,” to buff superhero; putting on a significant amount of muscle and weight for the role. However, this isn’t the only time the actor underwent a drastic body transformation. In between the first and second “Spidermans,” Tobey shed 25 pounds for his role in “Seabiscuit.” Whether he’s climbing walls or playing a jockey, Tobey is clearly committed to his craft.

6. Billy Crudup in “Watchmen” (2009)
Billy Crudup completely transformed his looks to play the role of Dr. Manhattan, the blue-hued super being in Zack Snyder’s “Watchmen.” To play the role, the actor had to don a skintight outfit, which emphasized every muscle. When many fans first saw him in 1999’s “Almost Famous,” he was a leaned out rock-star, but as a beefy Dr. Dr. Manhattan, this leading lad proved that he can play characters that are both brawn and brains.

5. Chris Evans in “Captain America: The First Avenger” (2011)
Chris Evans is hoping to capture Americans’ hearts this summer with his good looks in “Captain America: The First Avenger.” The actor has already channeled a classic superhero as the Human Torch in the two “Fantastic Four” films, proving that he was definitely born to play a superhero. However, he added on lots of muscle since then and shows off his well-defined physique even more while wearing the classic Avenger suit. However, his significant muscle growth put the fire out on his human torch role; he’s said that he won’t play that role again.

4. Jake Gyllenhaal in “Prince of Persia: The Sands of Time” (2010)
Jake Gyllenhaal may have played a prince in “Prince of Persia: The Sands of Time,” but he is a “king” of working out, sporting a buffed up body in his role as Dastan. When he first appeared in the film “Donnie Darko” in 2001, Jake had a leaner look, but this star worked hard to get ripped for this role. Jake has said he didn’t get ripped in the gym – he bulked up scaling walls and leaping over barricades.”[I] never did anything this intensive before [to change my body]. It’s a physical role. And when I commit to playing a part, it’s 110 percent,” Jake told People in April 2010, saying he studied the French martial art of Parkour – also referred to as “free running.”

3. Chris Hemsworth in “Thor” (2011)
Chris Hemsworth bulked up majorly for his warrior role in “Thor,” opening this coming weekend. This Australian up-and-comer has always been easy on the eyes, but he has gotten even meatier to play the Marvel comic-book hero. To transform from an Australian soap star in “Home and Away” (and one time Aussie “Dancing with the Stars” contestant!), to muscular god, Chris went on an intense diet and did so by eating lots and lots of chicken. “I put on about 20 pounds at one stage and then sort of pulled it back a bit,” he previously told Access. Eating large quantities of one amount of food is the price this actor had to pay in order to play the Norse “god of thunder.” “I’ve been pretty active, but eating that amount of food – it wasn’t the fun food – you know, it was dry chicken breast, it was pretty painful!”

2. Ryan Reynolds in “Blade Trinity” (2004)
Heartthrob Ryan Reynolds played a ripped Hannibal King in “Blade Trinity,” swapping his scrawny pretty boy image for brawny superhero and proving that he is much more than just a pretty-face. The well-built Ryan — who bared his chiseled abs in the film — went from a thin, college boy in 2002’s “Van Wilder” to super buff vampire hunter in “Blade Trinity.” Ryan may have done his share of rom-coms, but this young actor bulked up for the role and flaunted his biceps for the first time in this action packed film.

1. Hugh Jackman in “Wolverine” (2009)
Australian hunk Hugh Jackman buffed up four times for his role as Wolverine in the “X-Men” franchise. As he geared up to bear his famous metal claws, he revealed that it took a lot of calories to go from Broadway boy to throat ripping mutant in the action film. In transforming from a slender singing and dancing stage performer in “Oklahoma!” to slash ‘em up superhero Wolverine, Hugh packed on those meaty pounds with some carb-free cuisine and lots of lifting. “Just lifting anything,” he told Access’ Billy Bush at the 2011 Oscars. “He lifts me every day,” wife Deborra-Lee added with a laugh. He’s set to play Wolverine a fifth time in the planned sequel to the 2009 spin-off.

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