The Eyes of Cillian Murphy

The piercing eyes stare out intently from the cover of “American Prometheus,” a biography of J. Robert Oppenheimer, the scientist who spearheaded the development of the atomic bomb. The book, by Kai Bird and Martin Sherwin, was the inspiration for Christopher Nolan’s much-anticipated “Oppenheimer,” opening July 21. And as Nolan was working on the script, only one actor came to mind: Cillian Murphy.

“I try not to think of actors as I write, but Cillian’s eyes were the only eyes I know that can project that intensity,” Nolan said in a telephone interview. And there was another thing: “I knew he was one of the great actors of his generation.”

In “Oppenheimer,” as in most Nolan films (the Batman trilogy, “Dunkirk,” “Inception,” “Interstellar”), the scale is substantial. The director, who has managed to combine ambitious conceptual ideas with mainstream appeal and billion-dollar revenues, is one of Hollywood’s most admired and scrutinized creative figures. And although Murphy (whose first name is pronounced “KILL-ian) has worked regularly with Nolan for more than 20 years, he has until now played only supporting roles in his films.

Did he feel the pressure of carrying a film that arrives with Nolan-size expectations?

“Yes,” Murphy said seriously during a conversation in a north London photo studio, where he had just completed a shoot. The Irish-born actor, who turns 47 on Thursday, said that while playing a lead for Nolan was a dream, he took the time to prepare, “knowing you are working with one of the greatest living directors” — he paused. “I have been doing this for 27 years,” he said, adding an expletive for emphasis. “So I just threw myself in. I was terribly excited.”

OVER THE PAST DECADE, Murphy’s sapphire stare and coiled intensity have become familiar to millions of television viewers who have watched him play Tommy Shelby, the mesmerizing center of the British hit television series “Peaky Blinders,” even as he has maintained a thriving career onstage and in film.