- Leó Szilárd(as Leo Szilard)
- Werner Heisenberg(as W. Heisenberg)
- Otto Hahn(as O. Hahn)
- Niels Bohr(as N. Bohr)
- Leslie Groves(as L.R. Groves)
- Alexander Sachs(as A. Sachs)
- Fritz Strassmann(as Fritz Strassman)
- Sam Goudsmit(as Samuel A. Goudsmit)
- Carl Friedrich von Weizsäcker(as C.W. von Weizsäcker)
- Lew Kowarski(as Leo Kowarsky)
- Winston Churchill(Archivfilmmaterial)
- Albert Einstein(Archivfilmmaterial)
- Hermann Göring(Archivfilmmaterial)
- Adolf Hitler(Archivfilmmaterial)
- King Gustaf V(Archivfilmmaterial)
- Franklin D. Roosevelt(Archivfilmmaterial)
- Joseph Stalin(Archivfilmmaterial) (as Iosif Stalin)
- Harry S. Truman(Archivfilmmaterial)
