John Hurt as Narrator (voice)

Shuntaro Hida as Self - Hiroshima Survivor

Robert Austin as Winston Churchill

George Anton as Parsons

George Elsey as Self - Military Advisor

Paul Tibbets as Self - Pilot, Enola Gay

Theodore "Dutch" Van Kirk as Self - Navigator, Enola Gay

Akiko Takakura as Self - Hiroshima Survivor

Daniel Ben Zenou as Beser

Ed Bishop as Stimson

Katsumi Cho as Admiral Yonai

Noboru Akima as General Anami

Lee Colley as Van Kirk

Garry Cooper as Groves

Kenneth Jay as Harry Truman

Haruka Kuroda as Akiko Takakura

Tim Matthews as Major Thomas Ferebee

Shane Rimmer as James F. Byrnes

Fredrick Ruth as Robert Oppenheimer

J. Robert Oppenheimer as Self (archive footage)

Harry S. Truman as Self (archive footage)

Emperor Hirohito of Japan as Self (archive footage)