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

Rory Keane
Hartland Snyder

Michael Angarano
Robert Serber

Emma Dumont
Jackie Oppenheimer

Sadie Stratton
Mary Washburn

Britt Kyle
Barbara Chevalier

Guy Burnet
George Eltenton

Tom Jenkins
Richard Tolman

Louise Lombard
Ruth Tolman

Michael Andrew Baker
Joe Volpe

Jeff Hephner
Congressman

Olli Haaskivi
Edward Condon

David Rysdahl
Donald Hornig

Josh Peck
Kenneth Bainbridge

Jack Quaid
Richard Feynman

Brett DelBuono
Concerned Scientist

Gustaf Skarsgård
Hans Bethe

James Urbaniak
Kurt Gödel

Trond Fausa Aurvåg
George Kistiakowsky

Devon Bostick
Seth Neddermeyer

Danny Deferrari
Enrico Fermi

Christopher Denham
Klaus Fuchs

Jessica Erin Martin
Charlotte Serber

Ronald Auguste
J. Ernest Wilkins

Máté Haumann
Leo Szilard

Olivia Thirlby
Lilli Hornig

Jack Cutmore-Scott
Lyall Johnson

Harrison Gilbertson
Philip Morrison

James Remar
Henry Stimson

Will Roberts
George C. Marshall

Pat Skipper
James Byrnes

Steve Coulter
James Conant

Jeremy John Wells
AAF Officer

Sean Avery
Weatherman

Adam Kroeger
Army Captain

Drew Kenney
Soldier

Bryce Johnson
AAF Officer 2

Flora Nolan
Burn Victim

Kerry Westcott
Laughing Woman

Christina Hogue
Kissing Woman

Clay Bunker
Kissing Man

Tyler Beardsley
Weeping Man

Maria Teresa Zuppetta
Consoling Woman

Kate French
Presidential Aide

Gary Oldman
Harry Truman

Hap Lawrence
Lyndon Johnson

Meg Schimelpfenig
Senator's Assistant (uncredited)