"Oppenheimer," the blockbuster biopic about the race to build the first atomic bomb, claimed seven Academy Awards, including the prestigious Best Picture trophy on Sunday as Hollywood celebrated a triumphant year in film.

Irish actor Cillian Murphy won the Best Actor award for playing theoretical physicist J. Robert Oppenheimer, who led the U.S. effort in the 1940s to create a weapon that ended World War II. "Oppenheimer" director Christopher Nolan took home the directing Oscar.

"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."

A three-hour historical drama about science and politics, Oppenheimer became an unlikely box office hit, grossing $953.8 million and receiving widespread critical praise.

It was the first of Nolan's films to win best picture. The director has previously won acclaim for "The Dark Knight" Batman trilogy, "Inception," "Memento" and other movies.

As he accepted his gold statuette, Nolan noted that the movie business was a century old and still evolving.

"To know you think I'm a meaningful part of this means the world to me," he said.

Emma Stone was named best actress for playing a woman revived from the dead in the dark and wacky comedy "Poor Things." It was the second Academy Award for Stone, who landed the best actress honour for the 2016 musical "La La Land."

"This is really overwhelming," she said on stage.

The best actress race had been considered one of the tightest competitions, with Lily Gladstone nominated for "Killers of the Flower Moon." Had she prevailed, Gladstone would have been the first Native American to win an acting Oscar.

In supporting actor categories, Robert Downey Jr. of "Oppenheimer" and "The Holdovers" star Da'Vine Joy Randolph claimed their first Academy Awards.

Downey, who was nominated for an Oscar in 1993 before his career was derailed by drug use, won his honour on Sunday for playing Oppenheimer's professional nemesis, Lewis Strauss.

"I'd like to thank my terrible childhood and the Academy, in that order," Downey joked before he saluted his wife Susan, who he said found him as a "snarly rescue pet" and "loved him back to life."

Randolph received the Best Supporting Actress trophy for her role as a grieving mother and cafeteria worker in the comedy set in a New England boarding school.

"For so long, I always wanted to be different, and now I realise I just need to be myself," she said. "I thank you for seeing me."

Winners were chosen by the roughly 10,500 members of the Academy of Motion Picture Arts & Sciences.

After 2023 was marred by labour strikes by actors and writers, the Oscars gave Hollywood a chance to celebrate two blockbusters, "Oppenheimer" and "Barbie," which brought in a combined $2.4 billion at theatres and made movies the centre of pop culture last summer.

"Barbie" ended the night with one Oscar.

Billie Eilish and Finneas O'Connell landed the best original song for the ballad "What Was I Made For?" The pair had performed the song on stage earlier, with Eilish singing at a microphone next to O'Connell, her brother and co-writer, on piano.

The following is a complete list of Oscar winners at the 96th Academy Awards on Sunday, presented at a live, televised ceremony from Hollywood.

Best Picture
"Oppenheimer"

Best Actor
Cillian Murphy, "Oppenheimer"

Best Actress
Emma Stone, "Poor Things"

Best Director
Christopher Nolan, "Oppenheimer"

Best Supporting Actor
Robert Downey Jr., "Oppenheimer"

Best Supporting Actress
Da'Vine Joy Randolph, "The Holdovers"

Best Adapted Screenplay
"American Fiction"

Best Original Screenplay
"Anatomy of a Fall"

Best Animated Feature Film
"The Boy and the Heron"

Best Animated Short 
"War is Over! Inspired by the Music of John & Yoko"

Best International Feature
"The Zone of Interest," United Kingdom

Best Documentary Feature
"20 Days in Mariupol"

Best Documentary Short
"The Last Repair Shop"

Best Original Score
"Oppenheimer"

Best Original Song
"What Was I Made For?," "Barbie"

Best Sound
"The Zone of Interest"

Best Production Design
"Poor Things"

Best Live Action Short
"The Wonderful Story of Henry Sugar"

Best Cinematography
"Oppenheimer"

Best Makeup and Hairstyling
"Poor Things"

Best Costume Design
"Poor Things"

Best Visual Effects
"Godzilla Minus One"

Best Film Editing
"Oppenheimer"