Cillian Murphy understands why Matt Damon called him the ‘worst dinner companion imaginable’

Cillian Murphy has once again demonstrated the intensity of his commitment to acting—so much so that it once earned him the label of being “the worst dinner companion imaginable” from his Oppenheimer co-star Matt Damon.

Speaking in a recent interview on 60 Minutes, Murphy opened up about his experience working on Christopher Nolan’s biopic and the level of focus required to portray J. Robert Oppenheimer. When host Scott Pelley referenced Damon’s remark, Murphy responded with a laugh, acknowledging that there was some truth to it.

“Yeah, I mean, I've always been like that, I think,” Murphy said. “But it's because, to me, you have the time on set, which is short enough time — you have 10 hours, maybe. And then the other part, if you've got a significant part, you're having to keep your lines fresh.”

For Murphy, stepping into a major role means immersing himself completely, leaving little mental space for anything outside the character. That level of dedication, while essential to his craft, can make him less present in social situations during filming.

In addition to memorizing lines and maintaining character, Murphy highlighted the importance of rest in his routine. “And then the other big thing for me is sleeping. I love sleeping and I need sleep,” he added, underscoring the discipline behind his performance.

Despite this intense approach, Murphy made it clear that his relationship with Damon remains strong. “I have had lots of lovely dinners with him since the movie's finished,” he said, noting that things became far more relaxed once filming wrapped.

Oppenheimer features an all-star cast including Emily Blunt, Robert Downey Jr., Florence Pugh, and others, and has emerged as a major contender this awards season with 13 Oscar nominations, including Best Picture and Best Director for Christopher Nolan.

Murphy’s performance has drawn particular praise from his co-stars. Robert Downey Jr. described it as one of the most remarkable displays of dedication he has witnessed. “I have never witnessed a greater sacrifice by a lead actor in my career,” Downey said.

He also emphasized Murphy’s commitment to the demanding role. “He knew it was going to be a behemoth ask when Chris called him,” Downey explained. “But I think he also had the humility that is required to survive playing a role like this.”

Downey further illustrated Murphy’s work ethic with a revealing anecdote. While others in the cast considered relaxing during a break, Murphy remained focused on preparation. “We'd be like, ‘Hey, we got a three-day weekend… What are you going to do?’ ‘Oh, I have to learn 30,000 words of Dutch. Have a nice time.’”

These insights offer a glimpse into the level of discipline and sacrifice behind Murphy’s transformation in Oppenheimer. His ability to fully immerse himself—often at the expense of social interaction—is a defining part of his process.

For Murphy, disappearing into a role is not an exception but a necessity—one that continues to set him apart as one of the most compelling actors of his generation.