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)