Characters played by Brian Donlevy
Maj. Gen. Leslie R. Groves
Characters played by Robert Walker
Col. Jeff Nixon
Characters played by Tom Drake
Matt Cochran
Characters played by Beverly Tyler
Anne Cochran
Characters played by Audrey Totter
Jean O'Leary
Characters played by Hume Cronyn
Dr. J. Robert Oppenheimer
Characters played by Hurd Hatfield
Dr. John Wyatt
Characters played by Joseph Calleia
Dr. Enrico Fermi
Characters played by Godfrey Tearle
President Franklin D. Roosevelt
Characters played by Victor Francen
Dr. Marré
Characters played by Richard Haydn
Dr. Chisholm
Characters played by Jonathan Hale
Dr. Vannevar Bush
Characters played by John Litel
K.T. Keller
Characters played by Henry O'Neill
Gen. Thomas F. Farrell
Characters played by Warner Anderson
Capt. William S. Parsons U.S.N.
Characters played by Barry Nelson
Col. Paul Tibbetts Jr.
Characters played by Art Baker
President Harry S. Truman
Characters played by Ludwig Stössel
Dr. Albert Einstein
Characters played by John Hamilton
Dr. Harold C. Urey
Characters played by Frank Ferguson
Dr. James B. Conant
Characters played by Tom Stevenson
Dr. E. P. Wigner
Characters played by John Gallaudet
Dr. Leo Szilard
Characters played by Nella Walker
Grace Tully
Characters played by Edward Earle
Charles G. Ross
Characters played by Moroni Olsen
Dr. Arthur H. Compton
Characters played by Norman Lloyd
Dr. Troyanski
Characters played by Jim Davis
Pilot at Tinian
Characters played by Charles Trowbridge
Walter S. Carpenter Jr.
Characters played by Frank Wilcox
Dr. W. H. Zinn
Characters played by Henry Hall
Gen. Brehon Somervell
Characters played by Paul Harvey
Lt. Gen. W.D. Styer
Characters played by Larry Johns
Quaker Scientist
Characters played by Robert Emmett Keane
Dr. Rand
Characters played by James Bush
Dr. Ernest O. Lawrence
Characters played by Trevor Bardette
Clinic Doctor
Characters played by William Wright
Col. John Lansdale
Characters played by Damian O'Flynn
C. D. Howe
Characters played by Richard Abbott
Danish Underground Leader
Characters played by Philip Ahlm
Armed Guard
Characters played by John Albright
Quaker Scientist
Characters played by Erville Alderson
Secretary of War Henry Stimson
Characters played by Kirk Alyn
Scientist
Characters played by Rod Bacon
Crew Member
Characters played by Frank Baker
Canadian Officer
Characters played by Walter Baldwin
Workman
Characters played by John Banner
German Laboratory Assistant
Characters played by Gregg Barton
Enola Gay Navigator
Characters played by Holger Bendixen
German Submarine Commander
Characters played by Lee Bennett
Sergeant
Characters played by Joseph E. Bernard
Townsman
Characters played by Margaret Bert
Townswoman
Characters played by Robert Bice
Co-Pilot
Characters played by William Bishop
2nd Lieutenant - Electronics Officer
Enola Gay
Characters played by Carlyle Blackwell Jr.
Armed Guard
Characters played by Larry J. Blake
Tough Military Policeman
Characters played by Stanley Blystone
Civilian Guard
Characters played by John Bogden
Scientist
Characters played by Charles Bradstreet
Airport Guard
Characters played by Tex Brodus
Enola Gay Ground Crewman
Characters played by Paul Bryar
Army Officer
Characters played by Tom Burton
Officer
Characters played by Roy Butler
Townsman
Characters played by George M. Carleton
Senator
Characters played by James Carlisle
Industrialist
Characters played by Douglas Carter
Quaker Scientist
Characters played by Ed Cassidy
Rafferty
Characters played by Frank Chalfant
Scientist
Characters played by Spencer Chan
Japanese Naval Officer
Characters played by Peter Chong
Japanese General
Characters played by Bron Clifford
Chaplain
Characters played by Bruce Cowling
Enola Gay Ground Crewman
Characters played by Ralph Crane
Weatherman
Characters played by Frank Dae
Senator
Characters played by Bert Davidson
Armed Guard
Characters played by Boyd Davis
Senator
Characters played by Harry Denny
Passing Officer
Characters played by Tom Dillon
Gregor
Characters played by Ralph Dunn
Guard
Characters played by Dick Earle
Industrialist
Characters played by Helen Eby-Rock
Townswoman
Characters played by Blake Edwards
CIC Man
Characters played by Frank Erickson
Attendant
Characters played by Herbert Evans
Scientist
Characters played by Lloyd Everett
Enola Gay Ground Crewman
Characters played by Budd Fine
Evictee
Characters played by William Forrest
Brigadier General
Characters played by Ted French
Townsman
Characters played by Arno Frey
Nazi Official
Characters played by Paul Fung
Japanese Radar Officer
Characters played by Jack Gallagher
Evictee
Characters played by John Gannon
Orderly
Characters played by Stewart Garner
Communications Officer
Characters played by Kenneth Gibson
President Truman's Secretary
Characters played by Tom Gibson
Minor Role
Characters played by Frederick Giermann
Nazi Officer
Characters played by Bob Gilbert
Lieutenant - R.C.M.
Enola Gay
Characters played by Jon Gilbreath
Attendant
Characters played by William Graeff Jr.
Emergency Switch Operator
Characters played by Clarke Hardwicke
Enola Gay Co-Pilot
Characters played by Sam Harris
Scientist on Plane
Characters played by Harry Hayden
Harried Editor
Characters played by Bill Hickman
Barometric Observer
Characters played by Russell Hicks
General
Characters played by Earle Hodgins
Gate Guard
Characters played by Jimmie Horan
Soldier at Airfield
Characters played by James Horne Jr.
Barmetric Observer
Characters played by Anne Howard
English Laboratory Assistant
Characters played by Jimmy Hunt
Little Boy
Characters played by Selmer Jackson
Senior Engineer
Characters played by John James
Engineer
Characters played by William Janssen
Instrument Operator
Characters played by Bobby Jordan
Radioman on Tinian Receiving A-Bomb Message
Characters played by Tommy Kelly
Mack
Characters played by John B. Kennedy
Self - Newsreel Narrator
Characters played by Mike Killian
Senior Engineer
Characters played by Martin Kosleck
Dr. O. E. Frisch
Characters played by Paul Kruger
Construction Engineer
Characters played by Al Kunde
Evictee
Characters played by Peter Lawford
Member of Military Personnel
Characters played by Nolan Leary
Townsman
Characters played by Jack Lee
Gen. Groves' Aide
Characters played by William F. Leicester
Enola Gay Flight Engineer
Characters played by Frank Leigh
British General
Characters played by James B. Leong
Japanese Army Officer
Characters played by Weaver Levy
Japanese Sailor
Characters played by Donald S. Lewis
Secret Service Man
Characters played by King Lockwood
Col. Nichols
Characters played by Richard Loo
Japanese Officer
Characters played by Robert Malcolm
Keith
Characters played by Jack Manolas
Minor Role
Characters played by Chris-Pin Martin
Mexican Man
Characters played by Louis Mason
Workman
Characters played by Roger McGee
Scientist
Characters played by Michael McGrath
Dr. Kistiakonsky
Characters played by Malcolm 'Bud' McTaggart
Radio Operator
Characters played by Patricia Medina
Mrs. Wyatt
Characters played by Danny Merrill
Scientist
Characters played by Sybil Merritt
Cute Guide
Characters played by Torben Meyer
Milkman
Characters played by Howard M. Mitchell
Townsman
Characters played by Forbes Murray
Briefing Officer
Characters played by Merlyn Nelson
Evictee
Characters played by James Nolan
President Roosevelt's Bodyguard
Characters played by Wedgwood Nowell
Industrialist
Characters played by Larry Nunn
Worried GI
Characters played by Fred Nurney
Nazi Officer
Characters played by Ray Page
Meter Man
Characters played by Eddie Parks
Bewildered Civilian
Characters played by Charles Peck
GI Messenger
Characters played by Ray Pemberton
Electronics Engineer
Characters played by Bob Pepper
Crewman
Characters played by George Peters
Nurse
Characters played by Tom Pilkington
Man with Counter
Characters played by Otto Reichow
Nazi Officer
Characters played by William Roberts
Enola Gay Radio Operator
Characters played by Ellen Ross
Waitress
Characters played by Carl Saxe
German General's Aide
Characters played by Frank J. Scannell
Winne
Characters played by Jerry Schumacher
Nazi Officer
Characters played by Hans Schumm
Nazi Police Officer
Characters played by Dorothy Scott
Laboratory Assistant
Characters played by Robin Short
Young Scientist
Characters played by Leslie Sketchley
Soldier
Characters played by Buster Slaven
Enola Gay Assistant Gunner
Characters played by J. Lewis Smith
Wolfish Soldier
Characters played by Eunice Soo-Hoo
Japanese Child
Characters played by Robert Spencer
Nuclear Scientist
Characters played by Jack Sterling
Enola Gay Tail Gunner
Characters played by Bert Stevens
Man at Time Capsule Ceremony
Characters played by Cedric Stevens
Evictee
Characters played by William Tannen
Soldier at A-Bomb Test
Characters played by Richard Terry
Enola Gay Radarman
Characters played by David Thursby
English Bobby
Characters played by Frank Tomlinson
Minor Role
Characters played by George Travell
Tinian Co-Pilot
Characters played by H.T. Tsiang
Prof. Okani
Characters played by George Turner
Pilot
Characters played by Harry Tyler
Man
Characters played by William Van Vleck
Evictee
Characters played by Leslie Vincent
English Junior Scientist
Characters played by Emmett Vogan
Medical Major
Characters played by Hans von Morhart
Danish Customs Man
Characters played by Eddy Waller
Man
Characters played by Constance Weiler
Minor Role
Characters played by Harry T. Wensel
Wensel
Characters played by Carl Wester
Construction Engineer
Characters played by Guy Williams
Enola Gay Bombardier
Characters played by Ronald Wong
Japanese Child
Characters played by Jack Worth
Nazi Officer