Matthew McConaughey in "Dallas Buyers Club
McConaughey lost around 50 pounds to portray Ron Woodroof, an AIDS patient. His physical transformation, along with a powerful performance, earned him an Academy Award for Best Actor.
Charlize Theron in "Monster"
Theron underwent a dramatic transformation to portray serial killer Aileen Wuornos. She gained weight, wore prosthetic teeth, and completely altered her appearance, earning her an Academy Award for her remarkable performance.
Robert De Niro in "Raging Bull"
De Niro gained over 60 pounds to play the older version of boxer Jake LaMotta. He trained extensively and transformed his body to convincingly portray the character's physical decline.
Eddie Redmayne in "The Theory of Everything"
Redmayne portrayed renowned physicist Stephen Hawking, who suffered from motor neuron disease. He spent months studying Hawking's mannerisms and physical limitations,
Tilda Swinton in "Suspiria"
Swinton's transformation involved playing multiple roles, including an elderly male psychoanalyst. Through the use of prosthetics and impeccable acting, Swinton completely disappeared into each character, showcasing her remarkable versatility.
Gary Oldman in "Darkest Hour"
Oldman underwent an astonishing transformation to portray British Prime Minister Winston Churchill. Through the use of prosthetics and makeup, Oldman completely embodied Churchill's appearance, mannerisms, and distinctive voice.
Heath Ledger in "The Dark Knight"
Ledger's portrayal of the Joker involved a complete transformation. He immersed himself in the role, physically and mentally, creating a sinister and iconic character that earned him a posthumous Academy Award.
Christian Bale in The Machinist
Bale lost 63 pounds for his role as Trevor Reznik, an insomniac who weighs only 120 pounds. He did this by eating a very strict diet of one can of tuna and one apple per day.