Gary Oldman
Harry Truman
James Remar
Henry Stimson
Matt Damon
Leslie Groves
Casey Affleck
Boris Pash
Cillian Murphy
J. Robert Oppenheimer
Josh Hartnett
Ernest Lawrence
Robert Downey Jr.
Lewis Strauss
Tony Goldwyn
Gordon Gray
Emily Blunt
Kitty Oppenheimer
Pat Skipper
James Byrnes
Matthew Modine
Vannevar Bush
Kenneth Branagh
Niels Bohr
Michael Angarano
Robert Serber
Josh Peck
Kenneth Bainbridge
Matthias Schweighöfer
Werner Heisenberg
Rami Malek
David Hill
James D'Arcy
Patrick Blackett
Louise Lombard
Ruth Tolman
Gregory Jbara
Chairman Magnuson
Máté Haumann
Leo Szilard
Will Roberts
George C. Marshall
Scott Grimes
Counsel
Harry Groener
Senator McGee
David Krumholtz
Isidor Rabi
Olivia Thirlby
Lilli Hornig
James Urbaniak
Kurt Gödel
Christopher Denham
Klaus Fuchs
Josh Zuckerman
Rossi Lomanitz
Gustaf Skarsgård
Hans Bethe
Brett DelBuono
Concerned Scientist
Bryce Johnson
AAF Officer 2
Tom Conti
Albert Einstein
Alden Ehrenreich
Senate Aide
Tim DeKay
Senator Pastore
Jason Clarke
Roger Robb
Steve Coulter
James Conant
David Dastmalchian
William Borden
Trond Fausa Aurvåg
George Kistiakowsky
Devon Bostick
Seth Neddermeyer
Hap Lawrence
Lyndon Johnson
Jefferson Hall
Haakon Chevalier
Dane DeHaan
Kenneth Nichols
Harrison Gilbertson
Philip Morrison
John Gowans
Ward Evans
Sadie Stratton
Mary Washburn
Jessica Erin Martin
Charlotte Serber
Macon Blair
Lloyd Garrison
Jeff Hephner
Congressman
Benny Safdie
Edward Teller
Sean Avery
Weatherman
Guy Burnet
George Eltenton
Alex Wolff
Luis Alvarez
Emma Dumont
Jackie Oppenheimer
Jack Quaid
Richard Feynman
Dylan Arnold
Frank Oppenheimer
Kate French
Presidential Aide
Steven Houska
Senator Scott
Ted King
Senator Bartlett
Florence Pugh
Jean Tatlock
Danny Deferrari
Enrico Fermi
Olli Haaskivi
Edward Condon
Jack Cutmore-Scott
Lyall Johnson
Flora Nolan
Burn Victim
Kurt Koehler
Thomas Morgan
David Rysdahl
Donald Hornig
Christina Hogue
Kissing Woman
Rory Keane
Hartland Snyder
Drew Kenney
Soldier
Michael Andrew Baker
Joe Volpe
Jeremy John Wells
AAF Officer
Kerry Westcott
Laughing Woman
Adam Kroeger
Army Captain
Tom Jenkins
Richard Tolman
Ronald Auguste
J. Ernest Wilkins
Clay Bunker
Kissing Man
Petrie Willink
Dutch Student
Meg Schimelpfenig
Senator's Assistant (uncredited)
Tyler Beardsley
Weeping Man
Britt Kyle
Barbara Chevalier
Maria Teresa Zuppetta
Consoling Woman