The Australian actor takes on his biggest role to date in the science fantasy flick as Imperial Military Director Orson Krennic, acting opposite the franchise's original baddie.

Landing such a life-changing part at 47 years old came as a surprise to Ben, who felt pressure to deliver when sharing the screen with such a famous character.

"Look, it makes me very happy. It's a very big deal. It also speaks to something in me that's very personal, that is about that kid that goes and watches that film in 1977. So, for a guy who's been at it for several, several, several childhoods' length, I'm really touched to be doing it," he told Wall Street Journal.

"I think that when your first villain is Darth Vader, the bar is so high that they stand out. I don't know why they stand out like they do. I know why Darth Vader does. I think they are very well realised."

James Earl Jones, who voiced Darth Vader in the original trilogy from 1977 to 1983, voices his alter ego once more, however, a series of different actors stepped into the dark suit on set.

Quizzed on how he feels about allowing Star Wars to define his career from now on, Ben insists it's not a bad thing.

"Yeah, I suppose for probably a lot of people, maybe most people, that is what I'll be. That's all right. I've got no problem with that," he smiled.

Rogue One, about the Rebel Alliance fighting against Vader's Death Star weapon, also stars Felicity Jones, Forest Whitaker, Donnie Yen and Diego Luna.

And Diego has recently gushed about the movie's diversity. In particular, he's thrilled to be part of a project which represents the audience watching and hopes other films follow suit.

"Today you go to the cinema, and if you're not looking at the screen, and you turn, you see that diversity there, you know? And that has to be portrayed in the frame," he told People magazine.

Rogue One: A Star Wars Story begins to hit cinemas from 14 December (16).