Cillian Murphy as J. Robert Oppenheimer

Emily Blunt as Kitty Oppenheimer

Matt Damon as Leslie Groves

Robert Downey Jr. as Lewis Strauss

Florence Pugh as Jean Tatlock

Josh Hartnett as Ernest Lawrence

Casey Affleck as Boris Pash

Rami Malek as David Hill

Kenneth Branagh as Niels Bohr

Benny Safdie as Edward Teller

Jason Clarke as Roger Robb

Dylan Arnold as Frank Oppenheimer

Tom Conti as Albert Einstein

James D'Arcy as Patrick Blackett

David Dastmalchian as William Borden

Dane DeHaan as Kenneth Nichols

Alden Ehrenreich as Senate Aide

Tony Goldwyn as Gordon Gray

Jefferson Hall as Haakon Chevalier

David Krumholtz as Isidor Rabi

Matthew Modine as Vannevar Bush

Scott Grimes as Counsel

Kurt Koehler as Thomas Morgan

John Gowans as Ward Evans

Macon Blair as Lloyd Garrison

Harry Groener as Senator McGee

Gregory Jbara as Chairman Magnuson

Ted King as Senator Bartlett

Tim DeKay as Senator Pastore

Steven Houska as Senator Scott

Petrie Willink as Dutch Student

Matthias Schweighöfer as Werner Heisenberg

Alex Wolff as Luis Alvarez

Josh Zuckerman as Rossi Lomanitz

Rory Keane as Hartland Snyder

Michael Angarano as Robert Serber

Emma Dumont as Jackie Oppenheimer

Sadie Stratton as Mary Washburn

Britt Kyle as Barbara Chevalier

Guy Burnet as George Eltenton

Tom Jenkins as Richard Tolman

Louise Lombard as Ruth Tolman

Michael Andrew Baker as Joe Volpe

Jeff Hephner as Congressman

Olli Haaskivi as Edward Condon

David Rysdahl as Donald Hornig

Josh Peck as Kenneth Bainbridge

Jack Quaid as Richard Feynman

Brett DelBuono as Concerned Scientist

Gustaf Skarsgård as Hans Bethe

James Urbaniak as Kurt Gödel

Trond Fausa Aurvåg as George Kistiakowsky

Devon Bostick as Seth Neddermeyer

Danny Deferrari as Enrico Fermi

Christopher Denham as Klaus Fuchs

Jessica Erin Martin as Charlotte Serber

Ronald Auguste as J. Ernest Wilkins

Máté Haumann as Leo Szilard

Olivia Thirlby as Lilli Hornig

Jack Cutmore-Scott as Lyall Johnson

Harrison Gilbertson as Philip Morrison

James Remar as Henry Stimson

Will Roberts as George C. Marshall

Pat Skipper as James Byrnes

Steve Coulter as James Conant

Jeremy John Wells as AAF Officer

Sean Avery as Weatherman

Adam Kroeger as Army Captain

Drew Kenney as Soldier

Bryce Johnson as AAF Officer 2

Flora Nolan as Burn Victim

Kerry Westcott as Laughing Woman

Christina Hogue as Kissing Woman

Clay Bunker as Kissing Man

Tyler Beardsley as Weeping Man

Maria Teresa Zuppetta as Consoling Woman

Kate French as Presidential Aide

Gary Oldman as Harry Truman

Hap Lawrence as Lyndon Johnson

Meg Schimelpfenig as Senator's Assistant (uncredited)

Christine Heneise as Lady Bird Johnson (uncredited)