Cillian Murphy J. Robert Oppenheimer Emily Blunt Kitty Oppenheimer Matt Damon Leslie Groves Robert Downey Jr. Lewis Strauss Florence Pugh Jean Tatlock Josh Hartnett Ernest Lawrence Casey Affleck Boris Pash Rami Malek David Hill Kenneth Branagh Niels Bohr Benny Safdie Edward Teller Jason Clarke Roger Robb Dylan Arnold Frank Oppenheimer Tom Conti Albert Einstein James D'Arcy Patrick Blackett David Dastmalchian William Borden Dane DeHaan Kenneth Nichols Alden Ehrenreich Senate Aide Tony Goldwyn Gordon Gray Jefferson Hall Haakon Chevalier David Krumholtz Isidor Rabi Matthew Modine Vannevar Bush Scott Grimes Counsel Kurt Koehler Thomas Morgan John Gowans Ward Evans Macon Blair Lloyd Garrison Harry Groener Senator McGee Gregory Jbara Chairman Magnuson Ted King Senator Bartlett Tim DeKay Senator Pastore Steven Houska Senator Scott Petrie Willink Dutch Student Matthias Schweighöfer Werner Heisenberg Alex Wolff Luis Alvarez Josh Zuckerman Rossi Lomanitz Emma Dumont Jackie Oppenheimer Louise Lombard Ruth Tolman Jack Quaid Richard Feynman Steve Coulter James Conant Jeremy John Wells AAF Officer Gary Oldman Harry Truman