- Gregg Herken - Self - Author, "Brotherhood of the Bomb"
- Jennet Conant - Self - Author, "109 East Palace"
- David Eisenbach - Self - History Professor, Columbia University
- Alex Wellerstein - Self - Nuclear Historian
- Martin J. Sherwin - Self - Co-Author, "American Prometheus" (voice)
- Michio Kaku - Self - Theoretical Physicist
- Leslie Groves - Self - Director, Manhattan Project (voice) (archive footage)
- Charles Oppenheimer - Self - Grandson
- Robert Christy - Self - Theoretical Physicist (voice) (archive footage)
- Robert S. Norris - Self - Author, "Racing for the Bomb"
- Hideko Tamura - Self - Hiroshima Survivor (Age 10)
- Roy Glauber - Self - Scientist, Manhattan Project (voice) (archive footage)
- Edward Teller - Self - Theoretical Physicist (archive footage)
- Eleanor Roosevelt - Self (archive footage)
- Judy Woodruff - Self (voice) (archive footage)
- Adolf Hitler - Self (archive footage)
- Vladimir Putin - Self (archive footage)
- Xi Jinping - Self (archive footage)
- Albert Einstein - Self (archive footage)
- Christopher Cassel
- Christopher Cassel
- Molly O'Brien
- Liz Cole
- Joel Schneider
- Adriano Bravo
- Anna Drubich
- Dave Richards
Capítulo disponible en las siguientes plataformas: