‘Oppenheimer’ Cast and Historical Guide: The Real People Behind the First Atomic Bomb

Cillian Murphy stars as theoretical physicist J Robert Oppenheimer, known as the “father of the atomic bomb.” Oppenheimer was named the director of the Manhattan Project’s Los Alamos Laboratory in New Mexico. It’s here where Oppenheimer and his team developed the first atomic bomb for World War II. The bomb was detonated on July 16, 1945 in what is referred to as the Trinity test, with Oppenheimer present during the demonstration.

For Murphy, “Oppenheimer” marks his first time leading a Nolan movie in over 20 years. The two worked together on five previous features: Three Batman films, “Inception” and “Dunkirk.” Murphy revealed last year that in prepping to play Oppenheimer he skipped over all the mechanics of what makes an atom bomb and instead focused on the man himself.

“[I prepped by doing] an awful lot of reading,” Murphy recently told The Guardian. “I’m interested in the man and what [inventing the atomic bomb] does to the individual. The mechanics of it, that’s not really for me — I don’t have the intellectual capability to understand them, but these contradictory characters are fascinating.” 

Emily Blunt stars as Katherine “Kitty” Oppenheimer, who married J Robert Oppenheimer in 1940. Born in Germany, Kitty was a botanist and biologist whose early life was associated with the Communist party after she became the common-law wife of party member Joseph Dallet Jr. She met Oppenheimer in 1939 at the California Institute of Technology, where he was a part time physics teacher and she was assisting physicist Charles Lauritsen. They began an affair while she was still married to medical doctor Richard Stewart Harrison. Kitty left Harrison and married Oppenheimer in November 1940 after she became pregnant with their first child, Peter. The couple moved to Los Alamos in March 1943 so that Oppenheimer could work full time on his Manhattan Project duties. They had their second child there. The isolation of living in Los Alamos contributed to Kitty’s alcoholism. 

Matt Damon plays Leslie Groves, who was the director of the Manhattan Project. The group’s mission was to develop the first atomic bomb during World War II. Groves had previously overseen the construction of the Pentagon while serving as an officer in the United States Army Corps of Engineers. As director of the Manhattan Project, Groves approved Los Alamos, New Mexico as one of several testing sites for the development of the atomic bomb. He personally recruited Oppenheimer to lead the charge at Los Alamos, a divisive choice at the time as Oppenheimer lacked a Nobel Prize and administrative leadership experience. Groves was on site for the detonation of the first atomic bomb on July 16, 1945.

Robert Downey Jr. plays Lewis Strauss, who served two terms on the U.S. Atomic Energy Commission (AEC). Strauss was the organization’s chairman during his second term. He became an enemy of Oppenheimer’s due to the AEC’s controversial hearings in April 1954 that led to Oppenheimer’s security clearance being revoked. The hearings came as a result of Strauss becoming convinced that Oppenheimer was a Soviet spy. Strauss became convinced of the fact after Oppenheimer’s claim that the Soviets were four years behind the U.S. in nuclear weapons development got challenged. Strauss eventually asked FBI director J. Edgar Hoover to run surveillance on Oppenheimer, and the organization ran a wiretapping of Oppenheimer’s phones. Illegally-obtained conversations Oppenheimer had over the phone with lawyers and more were used by Strauss to stack the hearing’s odds against Oppenheimer.

Florence Pugh stars as Jean Tatlock, who had a relationship with Oppenheimer before and during his marriage to Katherine “Kitty” Oppenheimer. The two met at the University of California, Berkeley, where Tatlock was a graduate student and Oppenheimer was a physics professor. Tatlock was a member of the American Communist Party. The film shows the two first meeting at a members gathering that Oppenheimer is brought to by his brother, Frank, who also had ties to the American Community Party. Tatlock’s relationship with Oppenheimer was cited during Lewis Strauss’ AEC hearing because of her Communist ties. Tatlock died by suicide at the age of 29 after struggling with clinical depression. 

Ernest Lawrence, played by Josh Hartnett, was a nuclear physicist from Canton, South Dakota who was awarded the Nobel Prize in Physics in 1939 for his invention of the cyclotron, a particle accelerator that was the first cyclical machine of its kind. When audiences first meet Lawrence in the film, he’s in the process of building that machine at the University of California, Berkeley. It’s here where Lawrence and Oppenheimer became close friends. Lawrence is credited with recommending to Leslie Groves that Oppenheimer be named the director of the Manhattan Project’s Los Alamos research site. Lawrence went on to assist the Manhattan project with uranium-isotope separation.

Boris Pash, played by “Manchester by the Sea” Oscar winner Casey Affleck, was a military intelligence officer in the United States Army. During World War II, Pash was tasked with investigating potential Soviet spy activity within the University of California, Berkley’s radiation laboratory. Oppenheimer was included among those interrogated by Pash, who determined that Oppenheimer was not a Soviet spy but may be connected with the Communist party given his previous relationships (see Jean Tatlock above). Pash suggested Oppenheimer be accompanied by counter-intelligence agents while on site in Los Alamos.

David L. Hill was an associate experimental physicist at the University of Chicago’s Met Lab during the Manhattan Project. Acording to the Atomic Heritage Foundation: “On December 2, 1942, he was one of the 49 scientists who witnessed the world’s first nuclear reactor to go critical.” Hill was also one of 70 scientists and workers to sign the Szilard Petition, a document written by Leo Szilard petitioning President Truman to avoid dropping the atomic bombs on Japan. In the film, Hill pops up in the 1959 timeline to disrupt Lewis Strauss’ bid for U.S. Secretary of Commerce by revealing the devious tactics Strauss used during the AEC hearing that stripped Oppenheimer of his security clearance.

Niels Bohr, played by Christopher Nolan regular Kenneth Branagh, was a physicist from Copenhagen, Denmark who won the Nobel Peace Prize in Physics in 1922 for his work on quantum theory and atomic structure. He is famous for developing the Bohr model of the atom. Whereas the U.S. had the Manhattan Project to develop nuclear weapons, Britain had the Tube Alloys. Bohr was a member of this group and made several visits to the Manhattan Project’s Los Alamos site during the atomic bomb’s design process. He helped Oppenheimer with work on modulated neutron initiators. In the film, Bohr is one of Oppenheimer’s physicist heroes and he attends one of Bohr’s lectures in college.

“Uncut Gems” and “Good Times” co-director Benny Safdie stars as Edward Teller, a theoretical physicist from Budapest who is known as the “father of the hydrogen bomb.” He was included in Oppenheimer’s 1942 summer planning seminar for the Manhattan Project at the University of California, Berkeley, and he moved to the Manahattan Project’s Los Alamos site in 1943 and joined the Theoretical Division, which was overseen by Hans Bethe (played by Gustaf Skarsgård in the movie). As part of the Manhattan Project, Oppenheimer tasked Teller with researching uranium hydride and the mathematics behind a nuclear weapon implosion. He was one of the few scientists on location to watch the detonation of the first atomic bomb during the Trinity test. 

Harry S. Truman, the 33rd president of the United States, is played in “Oppenheimer” by Oscar winner Gary Oldman, whom Nolan worked with on the “Dark Knight” trilogy. The Manhattan Project started in 1942 under Franklin D. Roosevelt’s presidency. Truman served as his vice president and was notoriously not told about the Manhattan Project until he became president himself. As president, Truman authorized the first and only use of nuclear weapons in war against Hiroshima and Nagasaki in Japan. The bombs were dropped on August 6 and August 9, 1945. In the film, Truman assures Oppenheimer that the world will only see the president as a villain of history for dropping the bombs and not their maker himself.

“Harold & Kumar” and “The Santa Clause” actor David Krumholtz stars as Isidor Isaac Rabi, an American physicist who won the 1944 Nobel Prize in Physics for his discovery of nuclear magnetic resonance. His work on radar at the Massachusetts Institute of Technology’s Radiation Laboratory led him to be a consultant on the Manhattan Project. Rabi was called to testify at the AEC security hearing in 1954 and strongly defended Oppenheimer. In the film, Rabi is heard passionately telling the AEC board that Oppenheimer loved and defended his country through his actions in the Manhattan Project.

“Stranger Things” star Matthew Modine reunites with Christopher Nolan after “The Dark Knight Rises” to play Vannevar Bush in “Oppenheimer.” Bush was an American engineer who headed the U.S. Office of Scientific Research and Development during World War II. He helped sell the U.S. government on creating the Manhattan Project. Later during World War II, he joined the Interim Committee that advised president Harry S. Truman on nuclear weapons. Bush was present at the Trinity test and watched the detonation of the first atomic bomb.

Nolan regular David Dastmalchian plays William L. Borden, who served as the executive director of the United States Congress Joint Committee on Atomic Energy from 1949 to 1953. He is best known for writing a letter to FBI director J. Edgar Hoover that accused Oppenheimer of being a Soviet spy, which then led to the Atomic Energy Commission’s security hearing in 1954. The film positions Borden as a puppet of Lewis Strauss, as Strauss wanted to keep his hands dry in Oppenheimer’s public downfall. Borden went on to testify against Oppenheimer during the hearings.

Michael Angarano stars as Robert Serber, an American physicist who contributed to the Manhattan Project. He previously had worked for Oppenheimer at the University of California, Berkeley and the California Institute of Technology before he was recruited to join the Manhattan Project in 1941. Serber was also involved with a section of the Manhattan Project known as Project Alberta, which aided in the delivery of nuclear weapons during the atomic bombings of Hiroshima and Nagasaki.

“The Boys” star Jack Quaid plays Richard Feynman, a theoretical physicist from New York City who shared the 1965 Nobel Prize in Physics with Julian Schwinger and Shin’ichirō Tomonaga for work on quantum physics. Feynman joined the Manhattan Project’s Los Alamos operation and was made group leader of Hans Bethe’s Theoretical Division, where he developed the Bethe–Feynman formula for calculating the yield of a fission bomb.

Former “Drake and Josh” Nickelodeon star Josh Peck plays Kenneth Bainbridge, an American physicist known for his work on cyclotron research at Harvard University. Oppenheimer appointed him the director of the Trinity test. The demonstration was the first time an atomic bomb was detonated and took place July 16, 1945. In the film, it is Bainbridge who acts on Oppenheimer’s order to press the button to detonate the bomb. He allegedly told Oppenheimer after the atomic bomb’s first detonation, “Now we are all sons of bitches.” After witnessing the Trinity test, Bainbridge turned against the testing of nuclear weapons.

Olivia Thirlby, best known for performances in “Juno” and “Dredd 3D,” stars as Lilli Hornig, a feminist activist and scientist who joined the Manhattan Project efforts. Lilli and her husband, chemist and explosives expert Bruce Hornig, moved to Los Alamos together to work for Oppenheimer. She became a staff scientist for the Manhattan Project.

Dane DeHaan stars as Kenneth Nichols, a United States Army office from Cleveland, Ohio who worked on the Manhattan Project as a civil engineer. He later oversaw the production of plutonium as the head of the Manhattan Engineer District. Nichols eventually joined the Atomic Energy Commission in 1953 as a general manager and was involved in the security hearing against Oppenheimer. He believed Oppenheimer was a Communist and ruled in favor of stripping Oppenheimer of his AEC security clearance. The film positions Nichols as a mole who encouraged William L. Borden to report Oppenheimer’s alleged Soviet ties to the FBI.

Jason Clarke plays Roger Robb, a United States circuit judge who joined the Atomic Energy Commission as special counsel during the security hearing against Oppenheimer in 1954. The hearing lasted four weeks as Robb and a panel of AEC members interrogated Oppenheimer on the grounds that he was a Soviet spy. Robb was convinced Oppenheimer was a traitor and used dramatic interrogation methods during the hearing to make Oppenheimer appear as guilty as possible. Robb was known for his ruthless tactics. The board voted to strip Oppenheimer of his security clearance.

“Cloud Atlas” star James D’Arcy plays Patrick Blackett, an experimental physicist who won the 1948 Nobel Prize in Physics. He is notable in the science community for being the first person to prove that radioactivity can lead to the nuclear transmutation of one chemical element to another. Oppenheimer was one of his most notable students. Early in the film, it’s implied that Blackett was a harsh teacher who did not favor Oppenheimer. He tells Oppenheimer to stay behind while the class attends a lecture by Niels Bohr. A mentally unstable Oppenheimer injects cyanide into an apple on Blackett’s desk. Oppenheimer ultimately gets rid of the apple before Blackett can eat it.

Tony Goldwyn goes from playing the president on ABC’s “Scandal” to starring as Gordon Gray in “Oppenheimer.” Gray was an American attorney and national security government official during Harry Truman and Dwight Eisenhower’s presidential administrations. He was one of the leading members on the AEC committee during the security hearing against Oppenheimer. The film implies that Gray was against Oppenheimer from the start. Convinced Oppenheimer was a Soviet spy, Gray worked with Roger Robb to ensure the outcome of the AEC hearing was not in Oppenheimer’s favor.

Albert Einstein won the 1921 Nobel Prize in Physics and is regarded as the most influential theoretical physicist in history. He pops up throughout “Oppenheimer” as he was friendly with the title character. In real life, Einstein did not work on the Manhattan Project. However, he did join forces with colleagues such as Leó Szilárd, Edward Teller and Eugene Wigner to worn the U.S. government that Germany would win an atomic bomb race if the U.S. did not start getting plans together to create such a weapon. The group wrote a letter to President Roosevelt, which is credited with pushing the U.S. towards the creation of the Manhattan Project. 

“Hereditary” star Alex Wolff plays Luis Walter Alvarez, who won the 1968 Nobel Prize in Physics for his work on particle physics used in the hydrogen bubble chamber. He was a friend and close colleague of Ernest Lawrence (Josh Hartnett, see above) in the research labs at the University of California, Berkeley. It’s here where Lawrence created the cyclotron, which Alvarez used to produce and study tritium. In the film, Alvarez is with Lawrence and Oppenheimer when they get the news that an atom has been split open for the first time. In real life, Alvarez traveled to Los Alamos and worked on the Manhattan Project. 

Dylan Arnold stars as Oppenheimer’s brother, Frank. A particle physicist in his own right, Frank conducted research on behalf of the Manhattan Project and was called to Los Alamos by his brother to help prepare the layout and designs for the Trinity test. Frank is most important to Oppenheimer’s story because he was a member of the American Communist Party and invited his brother to attend party gatherings before the Manhattan Project was founded. Oppenheimer’s ties to his brother and more party members put him under scrutiny during the AEC security hearing.

Haakon Chevalier, played by “Game of Thrones” actor Jefferson Hall, was a French professor at the University of California, Berkeley who became friends with Oppenheimer in 1937. In the film, Oppenheimer befriends Chevalier at a Communist party. The two went on to create the university’s teachers’ union, which angered some of Oppenheimer’s scientist colleagues as the union threw benefits in support of leftist causes. Their friendship was one of the defining parts of the AEC security hearing, as Chevalier told Oppenheimer about Soviet attempts to infiltrate the Manhattan Project. Oppenheimer belatedly reported the information as to protect Chevalier’s identity, which the AEC hearing committee used in favor of stripping Oppenheimer of his security clearance.

Matthias Schweighöfer, best known for his role in Zack Snyder’s “Army of the Dead” franchise, appears briefly as Werner Heisenberg, the German theoretical physicist who won the 1932 Nobel Prize in Physics for the creation of quantum mechanics. Oppenheimer idolizes Heisenberg in the film and even has a brief visit with him before World War II begins. Heisenberg was not involved in the Manhattan Project and instead worked on Germany’s nuclear weapons program during the war. Knowing how brilliant Heisenberg was and how his genius could aid in Germany’s creation of atomic weapons is part of the reason Oppenheimer needed to move so quickly with the Manhattan Project in Los Alamos.