Cillian Murphy as J. Robert Oppenheimer in Oppenheimer (2023)
Image via Universal Pictures

The cast of ‘Oppenheimer’ and the real-life people they play

Christopher Nolan's epic is full of A-listers and world-changing figures from history.

Oppenheimer, Christopher Nolan’s upcoming biopic about American physicist J. Robert Oppenheimer, the father of the atomic bomb, features one of the most impressive casts in recent memory.

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Headed by Cillian Murphy, who will embody Oppenheimer himself, the ensemble also includes names like Robert Downey Jr., Emily Blunt, Florence Pugh, Matt Damon, Rami Malek, and Kenneth Branagh. And that’s only the beginning. 

The highly-anticipated historical drama will be distributed by Universal Pictures, marking Nolan’s first film since Memento (2000) outside of a Warner Bros. Pictures deal due to conflicts regarding theatrical and streaming policies. It will release on the same day as WB’s Barbie, directed by Greta Gerwig, which is set to be one of the biggest films of the year alongside Oppenheimer.

The film will take from Kai Bird and Martin J. Sherwin’s book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer. As per Deadline, the “pulse-pounding” narrative will center on the challenges Oppenheimer faced as he risked “destroying the world in order to save it.” Leading man Cillian Murphy has also teased that, in true Nolan fashion, Oppenheimer won’t be following your regular biopic formula.   

If the three-hour runtime and the hefty cast are any indication, Oppenheimer is set to be a dense retelling of one of the events that shaped our world. To help you prepare for the film, here’s a round-up of the entire cast list for Oppenheimer, as well as some background on their roles.

Cillian Murphy as J. Robert Oppenheimer 

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As director of Los Alamos Laboratory, created to coordinate the scientific research of the Manhattan Project, Oppenheimer is credited as one of the fathers of the atomic bomb during World War II. He will be played by acclaimed Peaky Blinders lead actor and long-time Nolan collaborator Cillian Murphy.

In an interview with The Guardian, Murphy described Oppenheimer as a “fascinating” and “contradictory character.” “Chris will call me up and I’m there,” Murphy said of working with Oppenheimer director Christopher Nolan. This will be their sixth project together after The Dark Knight trilogy, 2010’s Inception, and 2017’s Dunkirk.

Emily Blunt as Kitty Oppenheimer

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The incredibly versatile Sicario and Mary Poppins Returns actress will be playing the wife of J. Robert Oppenheimer, Kitty, short for Katherine. Kitty was a German-American biologist and botanist as well as a member of the American Communist Party. She met Oppenheimer in 1939 when she was still married, and the two began an affair. In 1940, after she became pregnant with Oppenheimer’s child, she filed for divorce, then married the physicist in November of that year. 

Florence Pugh as Jean Tatlock 

Florence Pugh
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One of Hollywood’s current most coveted actresses, Pugh will be taking on the role of Jean Tatlock, an American psychiatrist and journalist. She started a relationship with Oppenheimer when he was a professor and she was a student at Berkeley University in 1936, which continued well into his marriage to Kitty. Jean and Kitty’s affiliations with the American Communist Party became a security liability for Oppenheimer later on.

Robert Downey Jr. as Lewis L. Strauss

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Strauss was a member of the U.S. Atomic Energy Commission (AEC) when, in 1947, Oppenheimer became chairman of the General Advisory Committee of the AEC. The two had a hostile relationship, with Strauss reportedly inciting the process that eventually resulted in Oppenheimer’s security clearance being revoked in 1954. 

This will be Robert Downey Jr.’s biggest role since the conclusion of his legendary run as Iron Man in the Marvel Cinematic Universe.

Matt Damon as General Leslie Groves Jr. 

Photos by Neil Mockford/FilmMagic/MPI/Getty Images

Major General Leslie Richard Groves Jr. was the director of the Manhattan Project, overseeing most of its developments. He selected Oppenheimer as the head of the Los Alamos Laboratory, vouching for him when others questioned his suitability for the role.

Gustaf Skarsgård as Dr. Hans Bethe

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A German-American nuclear physicist, Bethe was appointed head of the Theoretical Division at Los Alamos Laboratory by Oppenheimer himself, which reportedly didn’t go down well with Edward Teller, a fellow Manhattan Project member (played by Benny Safdie). 

Skarsgård is best known for his TV roles in Vikings and Westworld and for belonging to the most talented actor family in Sweden.

Michael Angarano as Robert Serber

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You likely know him from TV series like Minx and This Is Us, and now Michael Angarano will be playing Robert Serber in 2023’s Oppenheimer. Serber penned The Los Alamos Primer, a set of lectures supplied to all incoming scientific staff that joined the Manhattan Project. He assisted in the dropping of the atomic bombs and was part of the first American team to assess the affected areas afterward. 

Josh Hartnett as Ernest Lawrence 

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A close friend and colleague of Oppenheimer’s at Berkeley, Lawrence named his son Robert after the physicist. He recommended Oppenheimer to General Leslie Groves Jr. (played by Damon) for the position of head of Los Alamos Laboratory. After the war, he banned Robert’s brother Frank Oppenheimer (played by Dylan Arnold) from Berkeley’s Radiation Laboratory, straining his relationship with Robert. He was critical of Oppenheimer’s communist associations and a transcript in which he criticized him was used in Oppenheimer’s security hearings.

Lawrence will be played by Josh Hartnett, who made headlines in 2021 after making a comeback in Guy Ritchie’s Wrath of Man, his first Hollywood movie in 14 years. Hartnett’s career sky-rocketed after his performance in Pearl Harbor in 2001, making him one of the biggest heartthrobs of the 2000’s.

Josh Peck as Kenneth Bainbridge

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Yep, even Josh Peck is in Oppenheimer. The Drake & Josh alum will be playing Kenneth Bainbridge, who joined Project Manhattan in 1943. In 1945, he oversaw the Trinity nuclear test, the first detonation of a nuclear weapon. As the bomb went off, Bainbridge reportedly turned to Oppenheimer and said, “Now we are all sons of b*tches.”

Kenneth Branagh as Niels Bohr

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Branagh is a recurring face in the Christopher Nolan cinematic mosaic, with roles in both Dunkirk and Tenet. In Oppenheimer, he’ll be playing Danish physicist, Dr. Niels Henrik David Bohr. Named after his co-developer, the Bohr model was a breakthrough in understanding atomic structure and quantum theory and landed the physicist the Nobel Prize in Physics in 1922. The son of a Jewish woman, Bohr escaped Nazi-occupied Denmark in 1943, meeting Oppenheimer at Los Alamos later that year. The “father of the atomic bomb” credits Bohr with an important contribution to the work on modulated neutron initiators.

Gary Oldman as Harry Truman

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Yet another film legend to be associated with Oppenheimer, Gary Oldman is set to feature in only one scene, according to the actor. The Oscar-winning veteran played the emblematic Jim Gordon in Christopher Nolan’s Dark Knight Trilogy and won Best Actor for his work in Darkest Hour. The 33rd president of the United States, Harry S. Truman authorized the detonation of nuclear bombs in the Japanese cities of Hiroshima and Nagasaki in 1945. He was the first and only president to use nuclear weapons in war.

Rami Malek as David Hill

Rami Malek
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Just how many Oscar winners can Nolan collect in one film, you ask? Well, Rami Malek is definitely a part of that list. The Bohemian Rhapsody and No Time To Die star plays American physicist David L. Hill. According to the Atomic Heritage Foundation, Hill worked under Enrico Fermi (played by Danny Deferrari) as an associate physicist at the University of Chicago’s Metallurgical Laboratory. He was among the 49 scientists present for the world’s first human-made self-sustaining nuclear chain reaction. He joined Los Alamos in 1954.

Casey Affleck as Boris Pash

Casey Affleck
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Affleck’s character in Oppenheimer is the Chief of Security for the Manhattan Project, Colonel Boris T. Pash. When World War II broke out, Pash was tasked with monitoring security breaches at the Berkeley Radiation Laboratory, for fear of Soviet spies stealing the Manhattan Project’s research. In 1943, Leslie Groves placed Pash in charge of organizing and directing the Alsos Mission, which would be investigating Nazi Germany’s atomic program.

Other cast and characters

  • Benny Safdie plays Edward Teller. Teller was also a part of the Theoretical Division at Los Alamos Laboratory and like Bethe, was there from the project’s inception.
  • Dylan Arnold plays Frank Oppenheimer, J. Robert’s younger brother who worked at Berkeley’s Radiation Laboratory under Ernest Lawrence (Josh Hartnett) from 1941 to 1945. He also aided Kenneth Bainbridge (Josh Peck) with the Trinity nuclear test in 1943. He was involved with the American Communist Party and blacklisted from teaching positions until 1957.
  • Emma Dumont plays Jackie Oppenheimer, Frank’s wife.
  • James Remar plays Harold Stimson, Secretary of War, and General Leslie Groves Jr.’s (Matt Damon) immediate supervisor.
  • Christopher Denham plays Klaus Fuchs, who worked under Hans Bethe (Gustaf Skarsgård) at the Los Alamos Laboratory.
  • Devon Bostick plays Seth Neddermeyer, the head of a group that focused on implosion research, which eventually became essential to the production of nuclear weapons.
  • Danny Deferrari plays Enrico Fermi, associate director of Los Alamos Laboratory and head of the F Division.
  • Tony Goldwin plays Gordon Gray, the chairman of the committee appointed by Lewis Strauss to discuss the revocation of Oppenheimer’s security clearance in 1954.
  • Jason Clarke plays Roger Robb, the Special Counsel to the Atomic Energy Commission hearing on Oppenheimer’s loyalty.
  • Jack Quaid plays Richard Feynman, an American theoretical physicist who worked under Hans Bethe (played by Gustaf Skarsgård) at Los Alamos, met with Niels Bohr (played by Kenneth Branagh) frequently, and was present at the Trinity nuclear test.
  • David Dastmalchian plays William L. Borden, the executive director of the Joint Committee on Atomic Energy who wrote a letter accusing Oppenheimer of being a Soviet spy.
  • Alex Wolff plays Luis Walter Alvarez, an American experimental physicist who worked at Los Alamos and at the University of Chicago with Enrico Fermi (played by Danny Deferrari).
  • Olvia Thirlby plays Lilli Hornig, a Czech-American scientist and feminist activist who worked at Los Alamos.
  • James D’Arcy plays Patrick Blackett, a British experimental physicist who was Oppenheimer’s head tutor at Cambridge University in 1925. It’s rumored Oppenheimer tried to poison Blackett with an apple laced with toxic chemicals.
  • Dane Dehaan plays Kenneth Nichols, an Army officer and civil engineer who worked on the Manhattan Project and was appointed military liaison officer to the AEC by Leslie Groves.

The list is completed by a long list of other actors, playing minor roles, including students. This cast is certainly a doozy. It looks like the film will most likely be a collection of important moments in Oppenheimer’s life, with a special focus on the creation of the atomic bomb and subsequent fallout.

Oppenheimer is expected to premiere on July 21, 2023 and is gearing up to be one of the biggest films of the year.

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Francisca Tinoco
Francisca is a pop culture enthusiast and film expert. Her Bachelor's Degree in Communication Sciences from Nova University in Portugal and Master's Degree in Film Studies from Oxford Brookes University in the UK have allowed her to combine her love for writing with her love for the movies. She has been a freelance writer and content creator for five years, working in both the English and Portuguese languages for various platforms, including WGTC.