Cillian Murphy calls Oppenheimer costar Robert Downey Jr the most ‘electrifying actor I’ve ever worked with’

Downey Jr played Oppenheimer’s nemesis, Atomic Energy Commission chairman Lewis Strauss

Cillian Murphy was full of praise for his Oppenheimer costar Robert Downey Jr.

The Irish actor, 47, stars as the eponymous “father of the atomic bomb” in Christopher Nolan’s new feature while Downey Jr, 58, plays his nemesis, Atomic Energy Commission chairman Lewis Strauss.

In a new interview with GQ, Murphy was asked about his intense preparation for the role.

“I knew the script more or less before we went into work, which isn’t something I’ve ever done before. Only in theatre, because there was so much text, and it was quite dense. I wanted to not be worried about the text when I went on the floor,” he said.

However, in his scenes with Iron Man star Downey Jr, Murphy revealed that a lot of their interactions were improvised.

“A lot of the scenes I have with Downey, it was quite loose and quite improvisational,” he said.

“I mean, acting with him was was was was just extraordinary. He’s just electrifying, the most available engaged, present, unpredictably brilliant actor I’ve ever worked with.”

Cillian Murphy (left) and Robert Downey Jr in ‘Oppenheimer’ (Melinda Sue Gordon/Universal Pictures)

The two actors have been trading compliments throughout the press run for Oppenheimer.

In a recent interview with People magazine, Downey Jr said of Murphy: “I have never witnessed a greater sacrifice by a lead actor in my career.

“He knew it was going to be a behemoth ask when [Nolan] called him. But I think he also had the humility that is required to survive playing a role like this.”

Demonstrating Murphy’s devotion, Downey Jr recalled: “We’d be like, ‘Hey, we got a three-day weekend. Maybe we’ll go antiquing in Santa Fe. What are you going to do?’ ‘Oh, I have to learn 30,000 words of Dutch. Have a nice time.’ But that’s the nature of the ask.”

Similarly, Emily Blunt, who plays Oppenheimer’s wife, biologist Kitty Oppenheimer, said Murphy skipped cast dinners due to the “monumental” pressure of the role.

Robert Downey Jr as Lewis Strauss (© Universal Pictures. All Rights Reserved.)

Best known for his work in the Marvel Cinematic Universe, Downey Jr holds two Academy Award nominations, which he received for his role as Charlie Chaplin in Richard Attenborough’s 1991 biopic, Chaplin, and for his comedic role in Ben Stiller’s satirical war comedy Tropic Thunder (2008).

In an interview with The New York Times, the actor said he was happy to have “regained my connection with a more purist approach to making movies” after his time playing a superhero.

After exiting the MCU in 2019, Downey Jr dived straight into an ill-advised Dr Dolittle remake (Dolittle), which was ridiculed by critics and fell flat at the box office.

“Dolittle was a two-and-a-half-year wound of squandered opportunity,” he told The NYT.

“Then old Chris Nolan calls, and getting to see the spartan, almost monastic way he approaches this art form, it was like going to the other side of the moon.”

Oppenheimer is out now in cinemas.