The casting process was so secretive that some cast members did not know which role they would be playing until they signed on. Robert Downey Jr., Matt Damon, and Emily Blunt took pay cuts to work on the film, with each earning $4 million in lieu of their usual $10–20 million upfront salary. Downey went to Nolan's house to read the script, which was printed in black on red paper. Downey would later describe Oppenheimer as "the best film" in which he has appeared to date. Blunt met Nolan in Los Angeles and, when she was offered the role of Katherine "Kitty" Oppenheimer, she enthusiastically accepted; she also contacted Murphy to get an expectation of what working with Nolan would be like. Asked to play the part of Leslie Groves, Damon—who had appeared in Nolan's Interstellar —was taking a break from acting as a result of negotiations with his wife in couples therapy, but signed on to Oppenheimer as he had reserved one exception: if Nolan offered him a role in a film. Nolan cast writer-director Benny Safdie as physicist Edward Teller after asking director Paul Thomas Anderson about his experience directing Safdie in Licorice Pizza (2021). Safdie had worked alongside a nuclear physicist at Columbia University while in high school. It is Nolan's first film since Insomnia (2002) to not feature Michael Caine. Glen Powell auditioned and was rejected for the role that went to Josh Hartnett.