Gen. Leslie Groves
Brian Dennehy
J. Robert Oppenheimer
David Strathairn
Lawrence Dane
Colonel Pash
Ron Frazier
Edward Teller
Olek Krupa
Bernie McInerney
Seth
John Pielmeier
Dwight D. Eisenhower
Ken Pogue
Groves's Commanding Officer
Gary Reineke
Alan Scarfe
Ralph A. Bard
John Seitz
Enrico Fermi
Tony Shalhoub
Leo Szilard
Michael Tucker
Trude Weiss
Ester Spitz
Colonel Nichols
Ron White
Eugen Wigner
Stephan Balint
Albert Einstein
Peter Boretski
Richard Feynman
Patrick Breen
Hans Bethe
Vlasta Vrana
Samuel Goudsmit
George Popovich
Klaus Fuchs
Lorne Brass
Lord Rutherford
Michael Sinelnikoff
Haakon Chevalier
Graham Haley
James F. Byrnes
Hume Cronyn
Michael Polanyi
Kliment Denchev
Ilse Polanyi
Diana Fajrajsl
Colonel Lansdale
Timothy Webber
Robert Wilson
Harry Strandjofski
Mrs. Wisnovsky
Lia Sargent
Jack Wisnovsky
David Gow
Shapp
Michael Farrell
Mrs. Trowbridge
Isabelle Mejias
Robert Serber
Jonathan Wise
Ed Condon
George R. Robertson
President Harry S. Truman
Richard Dysart
William 'Deke' Parsons
Dee McCafferty
Captain DeSilva
Tom Butler
T. O. Jones
Robert Morelli
James Tuck
Jon Baggaley
Harry Gold
David Bolt
Army Major
David Ferry
Fleischmann
Heinar Pillar
Haagen Kistiakowski
François Klanfer
George Kistiakowski
Joel Miller
Kenneth Bainbridge
Michael J. Reynolds
Gen. George Marshall
Hal Holbrook
William D. Leahy
Ed McGibbon
Paul Tibbets
Nicholas Kilbertus
Air Force Guard
Joe Cazalet
Chemist
Scott Thomson
Alfred MacCormack
Bob Clout
Army General
Roland Hewgill
John J. McCloy
Stan Gibbons
Allan Dulles
Terrence Labrosse
London Pedestrian
Delise Alison
British Jr. Officer
Alex Guard
Henry Stimson
Barnard Hughes
British Sr. Officer
Philip Spensley
Alexander Sachs
Frederick Neumann
General Pa Watson
Norris Domingue
Los Alamo Scientist (uncredited)
Steve Barry
Scientist (uncredited)
Arthur Holden
Leo Szilard's Prime Scientist (uncredited)
Romano Orzari
Dr. Arthur Compton
John McMartin
Franklin D. Roosevelt
David Ogden Stiers
Kitty Oppenheimer
Anne Twomey
Director
Joseph Sargent
Executive Producer
Aaron Spelling
Original Music Composer
Mason Daring
Makeup Department Head
Jocelyne Bellemare
Executive In Charge Of Production
Ken Gord
Book
Peter Wyden
Teleplay
David W. Rintels
Associate Producer
Josette Perrotta
Producer
E. Duke Vincent
Director of Photography
Kees Van Oostrum
Editor
Debra Karen
Production Design
Curtis A. Schnell
Art Direction
Guy Lalande
Key Makeup Artist
Gillian Chandler
Assistant Hairstylist
Serge Morache
Hairstylist
Benjamin Robin
Ronald J. Rolfe
Unit Manager
François Sylvestre
Unit Production Manager
Production Manager
Norman Henry
Third Assistant Director
Sylvain Arseneault
Normand Bourgie
Second Assistant Director
Sean Dwyer
First Assistant Director
Michael A. Williams
Costume Design
Renée April