For the horror movie from executive producer Guillermo del Toro, Chastain slipped into an entirely new persona, donning a short black wig and covering her arms in tattoos.
When MTV News spoke with Chastain about the look, she walked us through the development of her character, Annabel, and the real-life inspiration for her signature style.
While Annabel may only be a wannabe punk, Chastain and her director, Andy Muschietti, found inspiration in Crystal Castles lead singer Alice Glass.
"It's on the page that Annabel plays punk, and she plays bass in a punk band. She's not like Lisbeth Salander. She's not hardcore, full-on. She's like the girl who went to community college, hangs out with her friends, loves punk music, and plays bass. She'll never be famous. She's not incredibly good at it," Chastain said. "That's on the page. From there, talking to Andy, the director, we talked about look for that. He sent me pictures of Alice Glass. I thought, 'Oh, my God. She's so rad. That's a great idea for the character.' So that's where we started with the hair, thinking 'Alice Glass.' "
For Annabel's ink, it was a creative concept from Muschietti that gave some depth to the character detail. "Then the tattoos, [Muschietti] suggested the octopus, because when a tentacle gets stuck, it can detach," Chastain said. "I thought that's kind of a great idea for Annabelle, because she wants no responsibilities. She's constantly swimming away."
"Mama" opens in theaters today.