Cillian Murphy won the Oscar for best actor for his role in "Oppenheimer."

The actor, who portrayed physicist J. Robert Oppenheimer, the father of the atomic bomb, in "Oppenheimer," said he was "overwhelmed" to have won the award.

"I'm a very proud Irishman standing here tonight," he said. "We made a film about the man who created the atomic bomb and, for better or for worse, we're all living in Oppenheimer's world, so I would really like to dedicate this to peacemakers everywhere."

Murphy accepted the Oscar from a group of previous best actor winners, including Nicolas Cage, Matthew McConaughey, Brendan Fraser, Ben Kingsley and Forest Whitaker.

This awards season, Murphy has won a Golden Globe, a Screen Actors Guild Award and a BAFTA.

Other nominees in the category included Bradley Cooper for "Maestro," Colman Domingo for "Rustin," Paul Giamatti for "The Holdovers" and Jeffrey Wright for "American Fiction."

The Oscars paid tribute to those in the entertainment industry who died in the past year during the "In Memoriam" segment.

Michael Gambon, Chita Rivera, Alan Arkin, Julian Sands, Andre Braugher, Glynis Johns, Paul Reubens and Ryan O'Neal were among the stars who were remembered, as well as Mathew Perry, Richard Lewis, Lee Sun-Kyun and Carl Weathers.

During the segment, Andrea Bocelli sang "Time to Say Goodbye" with his son Matteo Bocelli.

“Oppenheimer” won the Oscar for best original score.

Ariana Grande and Cynthia Erivo presented the award to composer Ludwig Göransson. This is his second Oscar win and third nomination.

Upon accepting the award, Göransson thanked director Christopher Nolan for allowing him to collaborate with his wife, acclaimed violinist Serena McKinney.

Other nominees in the category included “American Fiction,” “Indiana Jones and the Dial of Destiny,” “Killers of the Flower Moon,” and “Poor Things.”

Billie Eilish and Finneas O'Connell won the Oscar for best original song.

The sister and brother duo's hit song, "What Was I Made For?" from "Barbie," marked the duo's second Oscar win for best original song. They previously won the award in 2022 for their song "No Time To Die" from the James Bond film of the same name.

During their acceptance speech, Eilish said she felt "so incredibly lucky" and "honored" to take home the award.

"Thank you for this," she said. "I'm so grateful for this song and for this movie and the way that it made me feel, and -- this goes out to everyone who was affected by the movie and how incredible it is."

Other nominees in the category included "The Fire Inside" by Diane Warren from "Flamin' Hot," "I'm Just Ken" by Mark Ronson and Andrew Wyatt from "Barbie," "It Never Went Away" by Jon Batiste from "American Symphony" and "Wahzhazhe (A Song For My People)" by Scott George from "Killers of the Flower Moon."