Oppenheimer is an upcoming biographical thriller film written and directed by Christopher Nolan, based on the 2005 book American Prometheus by Kai Bird and Martin J. Sherwin. The film stars Cillian Murphy as J. Robert Oppenheimer, an American theoretical physicist credited with being the "father of the atomic bomb" for his role in the Manhattan Project—the World War II undertaking that developed the first nuclear weapons, with a supporting ensemble cast that includes Emily Blunt, Matt Damon, Robert Downey Jr., Florence Pugh, Rami Malek, Benny Safdie, Michael Angarano, Josh Hartnett and Kenneth Branagh.