Directed by Justine Triet, the film features a screenplay co-written by Triet and Arthur Harari. Sandra Huller stars as a writer on a quest to clear her name in her husband's demise.
Nolan received the award, competing against nominees like Justine Triet for 'Anatomy of a Fall', Martin Scorsese for 'Killers of the Flower Moon', Yorgos Lanthimos for 'Poor Things', and Jonathan Glazer for 'The Zone of Interest'.
The Academy of Motion Picture Arts and Sciences' official X handle congratulated the actor, tweeting, "Cillian Murphy takes home Best Actor in a Leading Role! #Oscars."
The movie, centered on J. Robert Oppenheimer, the American theoretical physicist known as the father of the atomic bomb, featured Robert Downey Jr. portraying a retired Naval Reserve officer and influential figure in the US Atomic Energy Commission.
Both co-stars received supporting actor Oscar nominations this year, with Blunt for "Oppenheimer" and Gosling for "Barbie," playfully acknowledging their rivalry between the blockbusters.