William Shatner as Narrator

Edward Teller as Self - Nuclear Physicist

W.H.P. Blandy as Self - Commander Joint Task Force One (archive footage)

Frank H. Shelton as Self - Nuclear Weaponeer

Dwight D. Eisenhower as Self - U.S. President (archive footage)

Adlai Stevenson as Self - U.S Ambassador (1961-1965) to the UN (archive footage)

Randall William Cook as Newsreel Narrator (archive sound)

Nikolai Bulganin as Self (archive footage)

Winston Churchill as Self (archive footage)

Everett Dirksen as Self (archive footage)

Albert Einstein as Self (archive footage)

Enrico Fermi as Self (archive footage)

Reed Hadley as Self (archive footage)

Averell Harriman as Self (archive footage)

Adolf Hitler as Self (archive footage)

Hubert H. Humphrey as Self (archive footage)

John F. Kennedy as Self (archive footage)

Nikita Khrushchev as Self (archive footage)

Anastas Mikoyan as Self (archive footage)

Marilyn Monroe as Self (archive footage)

J. Robert Oppenheimer as Self (archive footage)

Franklin D. Roosevelt as Self (archive footage)

Dean Rusk as Self (archive footage)

Woodrow P. Swancutt as Self (archive footage)

Leó Szilárd as Self (archive footage)

Mark Tapscott as Announcer (archive footage)

Paul Tibbets as Self (archive footage)

Wernher von Braun as Self (archive footage)

John von Neumann as Self (archive footage)

Mao Zedong as Self (archive footage)

Roy Neal as Self (uncredited)