| Name | Character | Episodes |
|---|---|---|
| Leslie Nielsen | Lewis Strauss | 3 |
| Michael Ironside | Werner Heisenberg | 3 |
| Pier Paolo Capponi | Enrico Fermi | 3 |
| Maury Chaykin | Général Leslie Groves | 3 |
| Miki Manojlović | Edward Teller | 3 |
| Jacques Perrin | Frédéric Joliot-Curie | 3 |
| Jean-Paul Muel | Leo Szilard | 3 |
| Tom Rack | Robert Oppenheimer | 3 |
| Maud Rayer | Lise Meitner | 3 |