When an actor or actress is cast in a role, they must become the character. From the accent to movements, every detail is focused on and created for the role. Sometimes, the actors don’t look like their character and have to change their appearance, including haircuts and even getting into top-tip shape to bring these characters to life.

Many male actors bulk up when they are cast in major action roles and hit the gym hard before filming begins but the payoff on screen is worth the time. Chris Pratt transformed his body before he appeared in Guardians of the Galaxy for one shirtless scene.

Image courtesy of Famous/ACE/INFphoto.com

The male actors aren’t the only ones taking their workouts seriously. Female action stars like Demi Moore and Scarlett Johansson got into insane shape to play roles on the big screen.

TheCelebrityCafe.com is counting down the top ten actor transformations who bulked up for a role on the big screen. From the women who became action stars to incredible transformations from actors like Christian Bale to play Batman and Will Smith to play world famous boxer Muhammad Ali, these actors go the extra mile to bring these characters to life on the big screen.

[new page=Demi Moore- G.I. Jane]

10. Demi Moore- G.I. Jane

Demi Moore became a marine in her film G.I. Jane and her transformation was remarkable. She got rid of her slim figure and added many pounds of muscle to bring this character to life on the big screen.

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9. Scarlett Johansson- Captain America: The Winter Solider

In the Avengers, Scarlett Johansson is amongst many superheroes and even a God but she holds her own on the big screen and transformed into Black Widow. She bulked up for the role and this gave her character another level of believability when she is standing next to Thor and Iron Man.

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8. Will Smith-Ali

Will Smith transformed himself into world famous boxer Muhammad Ali and his transformation was Oscar worthy.

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7. Christian Bale- Batman Begins

When Christopher Nolan took over the Batman series for Warner Bros. he cast Christian Bale as Bruce Wayne/Batman. Bale had to transform into the Dark Knight and added muscle onto his already large frame. He completed this transformation and had audiences fully believing he was Batman.

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6. Mickey Rourke- The Wrestler

Mickey Rourke did a complete body transformation for his role in the Oscar-nominated The Wrestler.

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5. Chris Hemsworth - Thor

Chris Hemsworth was cast as a God in the Marvel cinematic universe and hit the gym to play the part. The result was not disappointing.

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4. Tom Hardy-The Dark Knight Rises

Tom Hardy was convincing as one of the most feared villains in the Batman universe because of his size and muscle in The Dark Knight Rises. Hardy transformed himself into this villain and was in truly incredible shape for the role.

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3. Hugh Jackman- X-Men

It is hard to think of anyone else playing the character of Wolverine in the X-Men universe other than Hugh Jackman, but when he was given the role, he had to completely transform himself into the superhero and he has maintained that shape throughout the many X-Men films.

[new page= Gerard Butler - 300]

2. Gerard Butler - 300

Gerard Butler completely transformed his body to play the role of King Leonidas in 300. It was believable that Butler could lead his men into battle. He added muscle and strength for this role and spent a large amount of time at the gym preparing for 300.

[new page=Chris Pratt ]

1. Chris Pratt - Guardians of the Galaxy

Chris Pratt went from his normal size in Parks and Recreation to out of this world superhero in Guardians of the Galaxy. Pratt became the role of Star Lord in personality and physically, his transformation was incredible considering he was shirtless for only one scene in the film.