The film cast includes two Oscar winners: Christian Bale & Penélope Cruz; and four Oscar nominees: Annette Bening, Jessie Buckley, Jeannie Berlin and Jake Gyllenhaal.
Christian Bale portrays Dr. Frankenstein's Monster. His youngest child, Joseph (also known as Rex), will have a small part. Joseph/Rex previously had a small part in Thor: Amor y trueno (2022), which his father also starred in.
In January 2024, while hosting the Governors' Awards (the honorary / lifetime achievement awards given by the Academy of Motion Picture Arts and Sciences, which presents the Oscars), comedian John Mulaney jokingly recounted a story about being asked to tape an audition for a small role in this movie: "Ladies and gentlemen, you're looking at me and you're thinking, 'Oh, great. Another goddamn stand-up comedian here to make fun of us at our sacred rituals.' Well, I'll have you know, I'm not such an outsider. I am quite sought after in the film world. I would like to share with you a real email that I got from my agents about thirty days ago. This is an actual email that they sent me on December 7th, [2023,] so you'll get an idea of who you're dealing with. 'John, in anticipation of our conversation attached, please find the untitled Maggie Gyllenhaal project written and to be directed by Maggie Gyllenhaal.' That makes sense. 'Emma Tillinger Koskoff, Osnat Handelsman, and Talia Kleinhandler are attached to produce for Warner Brothers. Christian Bale is negotiating to star opposite Jessie Buckley.' I know who one of those people is. 'There is no script available at this time.' Okay, I'm listening. 'Pending, pending your response to the material. Please use the attached sides to put yourself on tape for the role of Young Cop.' Let's, thank you. They really sent this to me. WME [the entertainment agency William Morris Endeavor] sent this to me, let me be clear. I'm not being OFFERED Young Cop. They're giving me the chance to throw my hat in the ring. And yes, I put myself on tape, and, no, I didn't get it, but. . . . Let's stop focusing on failure, all right? Enough failure. Tonight, there are only winners."
One of two adaptations of Mary Shelley's "Frankenstein" released in 2025. The other is Guillermo del Toro's Frankenstein (2025).