Cillian Murphy has undergone a weight loss transformation for his latest role.
The Peaky Blinders star has been recently snapped looking noticeably slender on the set of Oppenheimer in Princeton, New Jersey, USA.
The Irishman is playing titular character J. Robert Oppenheimer, the theoretical physicist known as the 'father of the atomic bomb'.
The film will see Murphy collaborate with director Christopher Nolan once again, with the pair having previously worked together on The Dark Knight trilogy, Inception and Dunkirk.
Speaking about the role earlier this year, 45-year-old Murphy told Esquire: "It's the first time he's [Nolan] cast me in a lead, which I'm still a bit in shock about, but I'm thrilled.
"It's a huge part and a lot of work. But, in my estimation, you're working with one of the greatest living directors, so you're in safe hands."
Based on the book American Prometheus: The Triumph And Tragedy of J. Robert Oppenheimer, which won the Pulitzer Prize, the film has been written by Kai Bird and Martin J. Sherman.
The movie will centre around the life of the former wartime head of the Los Alamos Laboratory and his involvement in the Manhattan Project – the code name for the US research into and development of nuclear weapons in the 1940s.
Murphy is just one of many huge stars in the cast, which will feature Emily Blunt as Oppenheimer's wife - biologist and botanist - Kitty, Matt Damon as Manhattan Project director Leslie Groves Jr., and Robert Downey Jr. as founding commissioner of the U.S. Atomic Energy Commission, Lewis Strauss.
Florence Pugh will play psychiatrist Jean Tatlock, Benny Safdie will feature as theoretical physicist Edward Teller, and Josh Hartnett will portray pioneering American nuclear scientist Ernest Lawrence.
Rami Malek, Michael Angarano, Alden Ehrenreich, Kenneth Branagh and Matthew Modine will also appear in the movie, while Gary Oldham has confirmed he has a small cameo in one scene.
But as with all Nolan productions, the details are being kept under wraps
"The difference with this one is the story is there, everybody knows what happened," Murphy said.
"But Chris is telling it in a different way, as with Chris you would expect. That's all I can say."
He added that he will be extensively researching the role - without any expectation of ever getting his head around the stuff his character was working on.
He explained: "There's a wealth of stuff out there and I will read it all. I am never, ever going to understand quantum mechanics, no matter how hard or how many times people try to explain it to me.
"There's 0.0001 per cent of the population on the planet who have the brainpower to understand that. But I can begin to understand, conceptually, what those guys were trying to do."
Oppenheimer is scheduled for release on 21 July 2023.Featured Image Credit: BBC/Getty Images