Oppenheimer (/ˈɒpənhaɪmər/ OP-ən-hy-mər) is a 2023 epic biographical thriller film written and directed by Christopher Nolan. Based on the 2005 biography American Prometheus by Kai Bird and Martin J. Sherwin, the film chronicles the career of American theoretical physicist J. Robert Oppenheimer. The story predominantly focuses on Oppenheimer's early studies, his direction of the Manhattan Project during World War II, and his eventual fall from grace due to his 1954 security hearing. The film stars Cillian Murphy as the title character, Emily Blunt as his wife, Katherine “Kitty”, Matt Damon as General Leslie Groves, head of the Manhattan Project, Robert Downey Jr. as Lewis Strauss, a senior member of the U.S. Atomic Energy Commission and Florence Pugh as psychiatrist and Oppenheimer’s mistress, Jean Tatlock. The ensemble supporting cast includes Josh Hartnett, Casey Affleck, Rami Malek, and Kenneth Branagh.