Robert Downey Jr. and Matt Damon have officially joined Cillian Murphy in the upcoming film Oppenheimer. This news comes shortly after Emily Blunt was also confirmed to star in the Universal project with Christopher Nolan set to direct. Oppenheimer has now become one of the most stacked upcoming feature projects that's currently slated for release in 2023. Robert J. Oppenheimer, a physicist who was involved in the Manhattan Project, was also known as the "father of the atomic bomb". With the exact plot details currently being kept under wraps, the story is expected to dramatize the creation of the nuclear weapon.

Cillian Murphy will be portraying the theoretical physicist who helped develop the atomic bomb during World War II. According to The Hollywood Reporter, Emily Blunt will be playing Oppenheimer's wife, Katherine "Kitty" Oppenheimer. Matt Damon will be playing Lt. Gen. Leslie Groves who is the director of the Manhattan Project, which is the U.S. research initiative that developed the first atomic bomb. Robert Downey Jr. will be playing Lewis Strauss, the infamous chairman of the Atomic Energy Commission who initiated hearings that questioned Oppenheimer's loyalty to the United States and famously had the scientist's security clearance revoked.

Christopher Nolan is confirmed to be directing the upcoming film, and has also wrote the script. His wife, Emma Thomas, is set as a producer alongside Charles Roven of Atlas Entertainment. The upcoming Universal project is based on American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird and the late Martin J. Sherwin. After being published back in 2005, the book had won the Pulitzer Prize. Universal will distribute Oppenheimer theatrically worldwide, and release the film in North America.

Universal is already calling the film an "epic thriller that thrusts audiences into the pulse-pounding paradox of the enigmatic man who must risk destroying the world in order to save it." Matt Damon will be coming off of starring in Ridley Scott's period drama The Last Duel, which he also co-wrote.

Robert Downey Jr. last starred in Dolittle, the talking animal adventure that Universal released last year in 2020. While Christopher Nolan is known for always having an ensemble cast with actors he has worked alongside with in the past, it is expected that Cillian Murphy, Emily Blunt, Robert Downey Jr., and Matt Damon are just the tip the of the iceberg of cast members set to star in Oppenheimer.

Universal had recently won the rights to the upcoming project in an intense bidding war against Paramount, Sony and Warner Bros. By choosing to work with Universal on his next feature, Christopher Nolan had severed his 20-year relationship with Warner Bros. His long-time union with Warner Bros., that backed all of his biggest movies in the past, grew strained during the COVID-19 pandemic after the studio announced its 2021 slate would all premiere on HBO Max on the same day as their respective theatrical releases. The upcoming Universal project is currently set for release on July 21, 2023. Oppenheimer also carries a $100 million production budget. This news originated at Variety.