Oppenheimer viewers had no idea President Truman was played by Gary Oldman

People who have been to see Oppenheimer at the cinema have only just realised that Gary Oldman was in it.

Obviously, Christopher Nolan’s historical epic has an absolutely stellar cast, with Cillian Murphy taking on the title role of scientist J. Robert Oppenheimer.

Murphy is joined in the ensemble by Emily Blunt, Matt Damon, Florence Pugh, Rami Malek, Josh Hartnett, Casey Affleck, and Robert Downey Jr. to name but a few.

However, one actor managed to go unspotted by a lot of people who have seen the movie, despite that fact he plays a key figure in the whole saga.

Admittedly, he’s not a main character, but he’s still the US president.

It’s Gary Oldman, playing Harry S. Truman.

Universal Pictures

It turns out that loads of people just didn’t realise he was in the film at all, let alone right in front of their faces playing one of the most significant politicians of the 20^th century.

Oldman has previous for this sort of thing, too.

If you remember, a few years ago he completely transformed his appearance for his role in Darkest Hour, playing the UK’s Second World War Prime Minister Winston Churchill.

He won an Oscar for that portrayal, and while he’s unlikely to be considered by the Academy for this performance, a lot of people were shocked and intrigued to see that he featured in this latest historical blockbuster.

One fan gushed: “Am I the only one who didn't realise that PRESIDENT TRUMAN in OPPENHEIMER was played by GARY OLDMAN?

“Absolutely freaking amazing actor!!”

Another person said: “I just learned Gary Oldman played Harry S. Truman in Oppenheimer.”

A third said: “Tell me why I needed to watch Oppenheimer twice to recognise who Gary Oldman is playing”

And so on and so forth.

Oldman has worked with Nolan in the past, as the now-65-year-old was in his Dark Knight trilogy, as future commissioner James Gordon.

Nolan and Oldman kept his appearance in this latest movie under wraps for a good while, with Oldman only revealing himself on the red carpet when the film was premiered.

Famously, the cast walked out of that premiere before the movie was even shown because of the SAG-AFTRA strike.

Karwai Tang/WireImage/Getty

In the movie, Oldman appears as an incredibly pleased US president, who congratulates a distraught and guilt-ridden Oppenheimer on the success of his newly-created weapon of mass destruction.

Oppenheimer goes on to state that he has ‘blood on his hands’, a comment that reportedly annoyed Truman at their real-life meeting after the bombings of Hiroshima and Nagasaki.

Murphy spoke about Oldman’s role in passing during a pre-release interview with EW.

He said: “For me, every day, I was working with the best actors in the world, every single day,

“You’d look at the call sheet and there’d be, like, Gary Oldman one day, and then Ken Branagh, and then these guys [his co-stars at the roundtable].

“It was very hard to be cynical when you’re working with that level of talent.”