Oppenheimer is a 2023 epic biographical drama film written, produced, and directed by Christopher Nolan. It follows the life of J. Robert Oppenheimer, the American theoretical physicist who helped develop the first nuclear weapons during World War II. Based on the 2005 biography American Prometheus by Kai Bird and Martin J. Sherwin, the film dramatizes Oppenheimer's studies, his direction of the Los Alamos Laboratory and his 1954 security hearing. Cillian Murphy stars as Oppenheimer, alongside Robert Downey Jr. as the United States Atomic Energy Commission member Lewis Strauss. The ensemble supporting cast includes Emily Blunt, Matt Damon, Florence Pugh, Josh Hartnett, Casey Affleck, Rami Malek, and Kenneth Branagh.

Oppenheimer was announced in September 2021. It was Nolan's first film not distributed by Warner Bros. Pictures since Memento (2000), due to his conflicts regarding the studio's simultaneous theatrical and HBO Max release schedule. Murphy was the first cast member to join, with the rest joining between November 2021 and April 2022. Pre-production began by January 2022, and filming took place from February to May. The cinematographer, Hoyte van Hoytema, used a combination of IMAX 65 mm and 65 mm large-format film, including, for the first time, selected scenes in IMAX black-and-white film photography. As with many of his previous films, Nolan used extensive practical effects, with minimal compositing.

Oppenheimer premiered at Le Grand Rex in Paris on July 11, 2023, and was theatrically released in the United States and the United Kingdom on July 21 by Universal Pictures. Its concurrent release with Warner Bros.'s Barbie was the catalyst of the "Barbenheimer" phenomenon, encouraging audiences to see both films as a double feature. Oppenheimer received critical acclaim and grossed $975 million worldwide, becoming the third-highest-grossing film of 2023, the highest-grossing World War II-related film, the highest-grossing biographical film and the second-highest-grossing R-rated film of all time at the time of its release.

The recipient of many accolades, Oppenheimer was nominated for thirteen awards at the 96th Academy Awards and won seven, including Best Picture, Best Director (Nolan), Best Actor (Murphy), and Best Supporting Actor (Downey). It also won five Golden Globe Awards (including Best Motion Picture – Drama) and seven British Academy Film Awards (including Best Film), and was named one of the top 10 films of 2023 by the National Board of Review and the American Film Institute.