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Who’s Who in Oppenheimer? Breaking Down Christopher Nolan's A-List Cast

Director Christopher Nolan has assembled an incredible cast for Oppenheimer. Here's a primer on who they play.

By Tara Bennett

Director Christopher Nolan once more turns his camera on history with his latest film, Oppenheimer, which opens exclusively in theaters on July 21. As writer and director, Nolan revisits the development of the Manhattan Project through the eyes of the "father of the atomic bomb," J. Robert Oppenheimer (Cillian Murphy). As a theoretical physicist, Oppenheimer was recruited by the United States to be the director of the Los Alamos Laboratory where he assembled some of greatest scientific minds of the time to develop weapons to aid the ending of World War II.

In documenting the grave moment in history, Nolan has also assembled an incredible ensemble cast to play Oppenheimer's inner circle of family and friends, as well as the scientists and military men who surrounded him as they raced to create the first atomic bomb which was detonated on July 16, 1945. 

WATCH NBC WEB EXCLUSIVE: "It Feels Very Intimate:" Cillian Murphy on Working with Christopher Nolan and His Prep for Oppenheimer

It's a complex story with a lot of players, so there's nothing wrong with studying up on names and faces that are integral to the narrative. To help, NBC Insider has compiled this cheat sheet for just some of the over 40 roles encompassing a laundry list of A-list and top-tier character actors. 

Cillian Murphy as J. Robert Oppenheimer

Cillian Murphy posing on the red carpet wearing a black suit.

As a Nolan five-timer, Murphy returns to the Nolan fold to take on the controversial figure of J. Robert Oppenheimer. The film's portrayal of the scientist is informed heavily by the Pulitzer Prize-winning book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer. The film aims to lay out the complex moral journey that Oppenheimer took, as a man of huge intellect with the power to change history forever via his creation. 

Emily Blunt as Katherine "Kitty" Oppenheimer

Emily Blunt attends an event wearing a red dress.

Emily Blunt plays Oppenheimer's wife, Katherine Oppenheimer, who was married three times before she met Robert. The film provides insight into the woman who was an accomplished biologist and botanist in her own right. However, she retired her career to become a mother and moved to Los Alamos with Robert and their children. During that period, she suffered from isolation and addiction, which caused friction in her marriage even though she was Oppenheimer's biggest champion.

Robert Downey Jr. as Lewis Strauss

Robert Downey Jr. attends an event wearing an all black suit.

A prime figure in the United States' WWII policy, Lewis Strauss, played by Downey Jr., was a founding commissioner of the Atomic Energy Commission in 1947. He was also a formidable figure pressing Oppenheimer in his development of the atomic bomb. An advocate for H-bomb testing as a means to shorten the war, Strauss and Oppenheimer often clashed due to their opposing views. 

Florence Pugh as Jean Tatlock

Florence Pugh attends Paris Fashion Week in a baby blue backless dress showing off her new short pink hair.

Oppenheimer had two influential women in his life, his wife Kitty and his mistress, Jean Tatlock. Pugh embodies the woman who was a Stanford-educated psychiatrist and engaged in a years-long romance with Oppenheimer. Robert proposed to her twice, and she declined, which led to him seeing Kitty. But Jean and Robert still continued their affair even after his marriage. Their relationship was eventually used against him in future security hearings. 

Matt Damon as Leslie Groves

Matt Damon attends the Tribeca Festival wearing a black suit.

Leslie Groves was an officer in the U.S. Army Corps. of Engineers who was made a Brigadiere General and appointed the lead on the Manhattan Project. He recruited Oppenheimer to the project and became one of his greatest defenders despite their oppositional political and world views. They had an unexpected friendship and partnership in making what would become one of the world's most feared inventions. 

Kenneth Branagh as Niels Bohr

Kenneth Branagh attends the Academy Awards wearing a navy blue suit.

The 1922 Nobel Prize winner in Physics, Niels Bohr was known and revered by Oppenheimer for his “Copenhagen Interpretation” of quantum mechanics. He was recruited by Oppenheimer to join the Manhattan Project in Los Alamos. The press notes for Oppenheimer describe Bohr as the Obi-Wan to Oppenheimer, as his chief counsel and one of the primary brains behind "the bomb."

Matthew Modine as Vannevar Bush

Matthew Modine attends an event wearing a navy and green plaid suit.

Actor Matthew Modine plays Vannevar Bush, who was the director of the newly formed Office of Scientific Research and Development. It was his division that sounded the alarm about other countries developing an atom bomb so he mobilized the military-industrial complex to enter the race to crack the code of fission. 

Benny Safdie as Edward Teller

Benny Safdie attends an event wearing a gray suit and pink tie.

History labels Edward Teller as “the father of the hydrogen bomb" and a mental foil to Oppenheimer. He was recruited by Oppenheimer but ended up being a difficult team player. He was at constant odds with Robert as they clashed over focus. Teller was intent on building more powerful hydrogen bombs, and was the loudest voice about their work potentially setting the Earth’s atmosphere on fire. Played by Benny Safdie, the actor admits he almost became a physicist before he decided on pursuing acting, so this role brings him full circle. 

Tom Conti as Albert Einstein

Tom Conti attends the Paddington 2 premiere wearing a navy suit with a red tie.

Tony Award winner Tom Conti dons the iconic hair and eyebrows to play theory of relativity scientists, Albert Einstein. It was his work that opened the door to being able to make the atomic bomb. Einstein consulted closely with Oppenheimer during the Manhattan Project. 

Oppenheimer opens exclusively in theaters on July 21. 

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