Daniel Day-Lewis refused to get out of his wheelchair while he filmed My Left Foot and damaged two ribs because of it — he insisted that the crew spoon-feed him.
Hilary Swank tried to “pass as a boy” by cutting her hair, binding her breasts, speaking in a lower register, and putting socks down the front of her pants while she prepared to play trans man Brandon Teena in Boys Don’t Cry.
Will Smith admitted he “went too far” while working on Emancipation and he got stuck in literal chains. He said he “wanted to feel the degradation of slavery,” but was on the “hyperventilating edge” when the prop master lost the key to the chains.
Jamie Foxx wore prosthetic eyelids so his eyes would be glued shut for 14 hours on filming days while he played Ray Charles in the movie Ray.
Leonardo DiCaprio slept inside of an animal carcass, ate raw bison meat, and was on the brink of hypothermia all while playing Hugh Glass in The Revenant.
Robert Pattinson masturbated on set to completion while portraying Salvador Dalí in Little Ashes.
Ashton Kutcher gave himself pancreatitis and was hospitalized twice (!!!!) while preparing to play Steve Jobs in Jobs.
Charlize Theron wore dentures, shaved off her eyebrows, had her hair thinned out and fried repeatedly, and gained 30 pounds to play serial killer Aileen Wuornos in Monster.
Forest Whitaker stayed in character while playing Ugandan dictator Idi Amin in The Last King of Scotland even off set — it was so intense his family stopped speaking to him.
Margot Robbie trained in ice skating for five hours a day, five days a week, for five months to play Tonya Harding in I, Tonya — she worked herself so hard she got a herniated disk in her neck.
Joaquin Phoenix totally abandoned his own sense of self, refused to talk to his family, and only lived as Johnny Cash for the entirety of filming Walk the Line.
Jennifer Lopez slept in Selena Quintanilla’s bed while she prepared to portray the singer in Selena.
Adrien Brody gave up his apartment, sold his car, disconnected his phones, and lost 30 pounds on a crash diet in order to play Wladyslaw Szpilman in The Pianist.
Gary Oldman gave himself nicotine poisoning after smoking $20,000 worth of Winston Churchill’s favorite cigars for Darkest Hour.
Colin Firth developed headaches, a pinched nerve in his arm, and a stutter of his own after portraying George VI in The King’s Speech.
Val Kilmer got so immersed in playing Jim Morrison in The Doors that he needed to get therapy just so he could come out of character.