- Sam Waterston
- Â Robert Oppenheimer 7 episodes, 1980
- John Carson
- Â Narrator 7 episodes, 1980
- Christopher Muncke
- Â Colonel Kenneth Nichols / ... 6 episodes, 1980
- Jana Shelden
- Â Kitty Oppenheimer / ... 6 episodes, 1980
- Edward Hardwicke
- Â Enrico Fermi 6 episodes, 1980
- David Suchet
- Â Edward Teller 6 episodes, 1980
- Manning Redwood
- Â General Leslie Groves 5 episodes, 1980
- Peter Whitman
- Â Robert Serber 5 episodes, 1980
- Matthew Guinness
- Â Hans Bethe 5 episodes, 1980
- Bob Sherman
- Â Ernest Lawrence 4 episodes, 1980
- John Morton
- Â Robert Wilson 4 episodes, 1980
- Garrick Hagon
- Â Frank Oppenheimer 4 episodes, 1980
- Barry Dennen
- Â Isidor Rabi 4 episodes, 1980
- Ron Berglas
- Â John Manley 3 episodes, 1980
- Liza Ross
- Â Jacky Oppenheimer 3 episodes, 1980
- Blain Fairman
- Â Robert Bacher 3 episodes, 1980
- Kate Harper
- Â Jean Tatlock 3 episodes, 1980
- Erica Stevens
- Â Charlotte Serber 3 episodes, 1980
- Peter Marinker
- Â Haakon Chevalier 3 episodes, 1980
- Peter Banks
- Â Joseph Volpe 2 episodes, 1980
- Phil Brown
- Â Lewis Strauss 2 episodes, 1980
- David Baxt
- Â Colonel John Lansdale 2 episodes, 1980
- Milton Johns
- Â George Kistiakowsky 2 episodes, 1980
- Anthony Forrest
- Â Rossi Lomanitz 2 episodes, 1980
- Colin Bennett
- Â Seth Neddermeyer 2 episodes, 1980
- Billy J. Mitchell
- Â Captain 'Deke' Parsons 2 episodes, 1980
- Rosemary Faith
- Â Mitzi Teller 2 episodes, 1980
- Christopher Malcolm
- Â Steve Nelson 2 episodes, 1980
- Sarah Brackett
- Â Priscilla Duffield 2 episodes, 1980
- Douglas Lambert
- Â Kenneth Bainbridge 2 episodes, 1980
- John Cassady
- Â F.B.I. Agent 2 episodes, 1980
- William Hootkins
- Â F.B.I. Agent 2 episodes, 1980
- Nigel Anthony
- Â Scientist 2 episodes, 1980
- Peter Carlisle
- Â H.U.A.C. Counsel 1 episode, 1980
- Alexander Knox
- Â Henry Stimson 1 episode, 1980
- Ed Devereaux
- Â General Wilhelm Styer 1 episode, 1980
- Roger Frazier
- Â Drill Sergeant 1 episode, 1980
- George Gabriel
- Â Harold Green 1 episode, 1980
- Michael Fitzpatrick
- Â Congressman 1 episode, 1980
- Daniel Foley
- Â Joseph Weinberg 1 episode, 1980
- Stuart Milligan
- Â Herbert Marks 1 episode, 1980
- John Orchard
- Â Sergeant 1 episode, 1980
- Don Fellows
- Â Army Chief 1 episode, 1980
- Carl Haugland
- Â Student 1 episode, 1980
- James Maxwell
- Â Lloyd Garrison 1 episode, 1980
- Michael Ryan
- Â Student 1 episode, 1980
- Robert MacLeod
- Â Navy Chief 1 episode, 1980
- Robert Henderson
- Â Scientist 1 episode, 1980
- Philip O'Brien
- Â Roger Robb 1 episode, 1980
- Douglas W. Iles
- Â Air Force Chief 1 episode, 1980
- David Oliver
- Â Emil Konopinski 1 episode, 1980
- Seymour Green
- Â Gordon Gray 1 episode, 1980
- Shane Rimmer
- Â Ed Condon 1 episode, 1980
- Jerry Harte
- Â J.C.A.E. Counsel 1 episode, 1980
- Robert Arden
- Â John McCloy 1 episode, 1980
- Dave Hill
- Â James Tuck 1 episode, 1980
- Ed Bishop
- Â General Tom Farrell 1 episode, 1980
- Alexander Davion
- Â Arthur Compton 1 episode, 1980
- Raymond Marlowe
- Â Businessman 1 episode, 1980
- Pat Starr
- Â Alice Smith 1 episode, 1980
- Gabor Vernon
- Â Leo Szilard 1 episode, 1980
- Alan Westbrook
- Â Reporter 1 episode, 1980
- James Berwick
- Â Air Force General 1 episode, 1980
- James Smith
- Â Dr. Harrison 1 episode, 1980
- Jeff Harding
- Â M.P. 1 episode, 1980
- Albert Welling
- Â Klaus Fuchs 1 episode, 1980
- Bob Sessions
- Â Thomas Finletter 1 episode, 1980
- Robert Robinson
- Â Senator Knowland 1 episode, 1980
- Colette Hiller
- Â Barbara Chevalier 1 episode, 1980
- Robert O'Neil
- Â G.A.C. Committee Member 1 episode, 1980
- Matt Zimmerman
- Â M.C. 1 episode, 1980
- Michael John Paliotti
- Â Sam Allison 1 episode, 1980
- Jay Benedict
- Â S.E.D. 1 episode, 1980
- Stephen Turner
- Â David Griggs 1 episode, 1980
- Ray Charleson
- Â William Borden 1 episode, 1980
- Gerramy Quarto
- Â S.E.D. 1 episode, 1980
- Marc Smith
- Â Lt. Colonel Boris Pash 1 episode, 1980
- Raymond Thompson
- Â Francis Cotter 1 episode, 1980
- James Waterston
- Â Peter Oppenheimer 1 episode, 1980
- Elizabeth Giles
- Â Toni Oppenheimer 1 episode, 1980
- Geri Peterson
- Â Woman 1 episode, 1980
- Declan Mulholland
- Â F.B.I. Agent 1 episode, 1980
- Tony Sibbald
- Â Captain 1 episode, 1980
- Audrey Hamilton
- Â Carol Chevalier 1 episode, 1980
- Ralph G. Morse
- Â British Scientist unknown episodes
- Mark McQuown
- Â Student unknown episodes
- Antonino B. Garcia
- Â US Army Soldier (uncredited) 7 episodes, 1980
