- C M
Cillian MurphyJ. Robert Oppenheimer
- E B
Emily BluntKitty Oppenheimer
- M D
Matt DamonLeslie Groves
- R D
Robert Downey Jr.Lewis Strauss
- F P
Florence PughJean Tatlock
- J H
Josh HartnettErnest Lawrence
- C A
Casey AffleckBoris Pash
- R M
Rami MalekDavid Hill
- K B
Kenneth BranaghNiels Bohr
- B S
Benny SafdieEdward Teller
- J C
Jason ClarkeRoger Robb
- D A
Dylan ArnoldFrank Oppenheimer
- T C
Tom ContiAlbert Einstein
- J D
James D'ArcyPatrick Blackett
- D D
David DastmalchianWilliam Borden
- D D
Dane DeHaanKenneth Nichols
- A E
Alden EhrenreichSenate Aide
- T G
Tony GoldwynGordon Gray
- J H
Jefferson HallHaakon Chevalier
- D K
David KrumholtzIsidor Rabi
- M M
Matthew ModineVannevar Bush
- S G
Scott GrimesCounsel
- K K
Kurt KoehlerThomas Morgan
- J G
John GowansWard Evans
- M B
Macon BlairLloyd Garrison
- H G
Harry GroenerSenator McGee
- G J
Gregory JbaraChairman Magnuson
- T K
Ted KingSenator Bartlett
- T D
Tim DeKaySenator Pastore
- S H
Steven HouskaSenator Scott
- P W
Petrie WillinkDutch Student
- M S
Matthias SchweighöferWerner Heisenberg
- A W
Alex WolffLuis Alvarez
- J Z
Josh ZuckermanRossi Lomanitz
- R K
Rory KeaneHartland Snyder
- M A
Michael AngaranoRobert Serber
- E D
Emma DumontJackie Oppenheimer
- S S
Sadie StrattonMary Washburn
- B K
Britt KyleBarbara Chevalier
- G B
Guy BurnetGeorge Eltenton
- T J
Tom JenkinsRichard Tolman
- L L
Louise LombardRuth Tolman
- M A
Michael Andrew BakerJoe Volpe
- J H
Jeff HephnerCongressman
- O H
Olli HaaskiviEdward Condon
- D R
David RysdahlDonald Hornig
- J P
Josh PeckKenneth Bainbridge
- J Q
Jack QuaidRichard Feynman
- B D
Brett DelBuonoConcerned Scientist
- G S
Gustaf SkarsgårdHans Bethe
- J U
James UrbaniakKurt Gödel
- T F
Trond Fausa AurvågGeorge Kistiakowsky
- D B
Devon BostickSeth Neddermeyer
- D D
Danny DeferrariEnrico Fermi
- C D
Christopher DenhamKlaus Fuchs
- J E
Jessica Erin MartinCharlotte Serber
- R A
Ronald AugusteJ. Ernest Wilkins
- M H
Máté HaumannLeo Szilard
- O T
Olivia ThirlbyLilli Hornig
- J C
Jack Cutmore-ScottLyall Johnson
- H G
Harrison GilbertsonPhilip Morrison
- J R
James RemarHenry Stimson
- W R
Will RobertsGeorge C. Marshall
- P S
Pat SkipperJames Byrnes
- S C
Steve CoulterJames Conant
- J J
Jeremy John WellsAAF Officer
- S A
Sean AveryWeatherman
- A K
Adam KroegerArmy Captain
- D K
Drew KenneySoldier
- B J
Bryce JohnsonAAF Officer 2
- F N
Flora NolanBurn Victim
- K W
Kerry WestcottLaughing Woman
- C H
Christina HogueKissing Woman
- C B
Clay BunkerKissing Man
- T B
Tyler BeardsleyWeeping Man
- M T
Maria Teresa ZuppettaConsoling Woman
- K F
Kate FrenchPresidential Aide
- G O
Gary OldmanHarry Truman
- H L
Hap LawrenceLyndon Johnson
- M S
Meg SchimelpfenigSenator's Assistant (uncredited)
