Oppenheimer is an upcoming biographical film written and directed by Christopher Nolan and starring Cillian Murphy as J. Robert Oppenheimer, the 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. A co-production between the United Kingdom and the United States, the film is based on American Prometheus, a biography written by Kai Bird and Martin J. Sherwin. The supporting cast includes Emily Blunt, Robert Downey Jr., Matt Damon, Rami Malek, Florence Pugh, Benny Safdie, Michael Angarano, Josh Hartnett and Kenneth Branagh. It is a co-production between Universal Pictures, Syncopy Inc. and Atlas Entertainment, with Nolan producing the film alongside Emma Thomas and Charles Roven.