Hollywood stars transform right in front of our eyes to play in films their different roles. From complete makeovers, some were the most dramatic of all. Discover them here.

For his appearance in The Machinist, Christian Bale lost more than 60 pounds.

Christian Bale in "The Machinist"

Bale worked his way from The Machinist's emaciated frame to bulking up for Batman Begins. His body transformation is one of the most widely talked-about in Hollywood.

Charlize Theron underwent an intense physical transformation for her role as serial killer Aileen Wuornos in Monster.

Charlize Theron underwent an intense physical transformation for her role as serial killer Aileen Wuornos in Monster.

Charlize Theron in "Monster"

She gained some weight, used prosthetics, and transformed her features completely. Her portrayal of Wuornos is one of the most chilling and convincing portrayal in the history of cinema.

When Chris Hemsworth sported his iconic muscular physique as Thor, he changed it off throughout Avengers: Endgame because Thor gained weight

Chris Hemsworth in "Thor" vs. "Avengers: Endgame" 

For Endgame, Hemsworth used a prosthetic belly and became the other version of Thor, which also told so much about him as an actor and his commitment to the character's journey.

Matthew McConaughey lost over 40 pounds to play Ron Woodroof in Dallas Buyers Club. For this extreme weight loss, he received immense praise

Matthew McConaughey in "Dallas Buyers Club"

McConaughey's dramatic weight loss epitomized the dedication to the character he was portraying. His body hurt in ways that were unbelievable to his fans as he portrayed a man with AIDS

Natalie Portman, however, underwent rigorous training for her character of playing a ballet dancer in Black Swan. She took months of class in ballet and losing weight.

Natalie Portman in "Black Swan"

Portman's dedication to playing a convincing ballerina took her to an Oscar win performance. She had to endure numerous hours of training just to be able to play the role of Nina.