 J. Robert OppenheimerSelf (archive footage) | Self (archive footage) |
| EEllen Bradbury ReidSelf - Daughter of Los Alamos Scientist | Self - Daughter of Los Alamos Scientist |
 Christopher NolanSelf - Writer / Director, "Oppenheimer" | Self - Writer / Director, "Oppenheimer" |
 Jon ElseSelf - Filmmaker, "The Day After Trinity" | Self - Filmmaker, "The Day After Trinity" |
 Kai BirdSelf - Co-Author, "American Prometheus" | Self - Co-Author, "American Prometheus" |
 Bill NyeSelf - Science Educator | Self - Science Educator |
| RRichard RhodesSelf - Author, "The Making of the Atomic Bomb" | Self - Author, "The Making of the Atomic Bomb" |
| MMareena Robinson SnowdenSelf - Nuclear Security Expert | Self - Nuclear Security Expert |
| AAlan B. CarrSelf - Senior Historian, Los Alamos National Laboratory | Self - Senior Historian, Los Alamos National Laboratory |
| GGregg HerkenSelf - Author, "Brotherhood of the Bomb" | Self - Author, "Brotherhood of the Bomb" |
| JJennet ConantSelf - Author, "109 East Palace" | Self - Author, "109 East Palace" |
| DDavid EisenbachSelf - History Professor, Columbia University | Self - History Professor, Columbia University |
| AAlex WellersteinSelf - Nuclear Historian | Self - Nuclear Historian |
 Martin J. SherwinSelf - Co-Author, "American Prometheus" (voice) | Self - Co-Author, "American Prometheus" (voice) |
 Michio KakuSelf - Theoretical Physicist | Self - Theoretical Physicist |
 Leslie GrovesSelf - Director, Manhattan Project (voice) (archive sound) | Self - Director, Manhattan Project (voice) (archive sound) |
| CCharles OppenheimerSelf - Grandson | Self - Grandson |
| RRobert ChristySelf - Theoretical Physicist (voice) (archive sound) | Self - Theoretical Physicist (voice) (archive sound) |
| RRobert S. NorrisSelf - Author, "Racing for the Bomb" | Self - Author, "Racing for the Bomb" |
| HHideko TamuraSelf - Hiroshima Survivor (Age 10) | Self - Hiroshima Survivor (Age 10) |
| RRoy GlauberSelf - Scientist, Manhattan Project (voice) (archive sound) | Self - Scientist, Manhattan Project (voice) (archive sound) |
 Edward TellerSelf - Theoretical Physicist (archive footage) | Self - Theoretical Physicist (archive footage) |
 Eleanor RooseveltSelf (archive footage) | Self (archive footage) |
 Judy WoodruffSelf (voice) (archive sound) | Self (voice) (archive sound) |
 Adolf HitlerSelf (archive footage) | Self (archive footage) |
 Vladimir PutinSelf (archive footage) | Self (archive footage) |
 Xi JinpingSelf (archive footage) | Self (archive footage) |
 Albert EinsteinSelf (archive footage) | Self (archive footage) |
