The win caps a very successful awards season for the 47-year-old Irish actor, who also picked up a Golden Globe, a Bafta, and a Screen Actors Guild award for his performance. It was his first Oscar nomination.
“We made a film about the man who created the atomic bomb, and for better or worse we are living in Oppenheimer’s world,” Murphy said as he held his trophy on stage. “So I would really like to dedicate this to the peacemakers everywhere.”
Murphy beat out fellow nominees Bradley Cooper, Colman Domingo, Paul Giamatti and Jeffrey Wright.
In what, expectedly, proved to be a big night for the best picture-winning “Oppenheimer”, British-American filmmaker Christopher Nolan similarly won his first Oscar for best director.
He had been favoured to win the Oscar after earning best director awards at the Golden Globes, Bafta, Critics Choice, and Directors Guild of America this year.
In his acceptance speech, Nolan thanked Universal and its executive Donna Langley, who made a big bet on the film, and also praised his cast and his family.
Nolan noted that movies are just a little bit over 100 years old and thanked the Academy for the honour.
“We don’t know where this incredible journey is going from here,” Nolan said. “But to know that you think I am a meaningful part of it means the world to me.”
Nolan also wrote the screenplay for “Oppenheimer” and produced the film with his wife Emma Thomas. The film has received 13 Oscar nominations overall, including wins for editing and cinematography, and has earned more than US$957 million at the global box office.
Earlier, Robert Downey Jr took home the prize for best supporting actor.
Nolan is known for his cerebral films and was first nominated for an Oscar for screenwriting in 2002 for “Memento”, which he also directed. He was nominated for best director in 2019 for the World War II movie “Dunkirk”.
Meanwhile, Murphy, who lives in Ireland and keeps a low profile in Hollywood, had his biggest role to date playing a tortured, morally ambiguous Oppenheimer.
He is also known for leading roles in films including “28 Days Later” and crime show “Peaky Blinders”, and for appearances in other Nolan projects, including the “Dark Knight” Batman trilogy and “Inception”.