Campbell Scott
Self - Narrator (voice)
Boyd Gaines
Chairman Gray (voice)
Daniel Gerroll
Colonel Pash
Michael Stuhlbarg
Edward Teller
E
Ellen Katz
The Stenographer
Michael Cumpsty
H
Harold Agnew
Self
J
Jeremy Bernstein
Self
Freeman Dyson
Self
R
Richard Rhodes
Self
Martin J. Sherwin
Self
Joseph McCarthy
Self (archive footage)
J. Robert Oppenheimer
Self (archive footage)
David Strathairn
J. Robert Oppenheimer
H
Herbert York
Self
M
Marvin L. Goldberger
Self
P
Priscilla McMillan
Self
R
Robert Christy
Self
R
Roy Glauber
Self
Harry S. Truman
Self (Archive Footage)
J. Edgar Hoover
Self (archive footage)
Lewis Strauss
Self (archive footage)
Dwight D. Eisenhower
Self (archive footage)
Eleanor Roosevelt
Self (archive footage)
Edward Teller
Self (archive footage)
Lyndon B. Johnson
Self (archive footage)