Christopher Walken is set to play Emperor Shaddam IV in 'Dune: Part Two'.

The 79-year-old Hollywood legend has joined the star-studded cast of Denis Villeneuve's second half of his adaptation of the sci-fi cult classic.

He joins new additions, Florence Pugh, as the Emperor’s daughter, Princess Irulan, and Austin Butler as Feyd-Rautha Harkonnen.

Walken's alter ego and Stellan Skarsgård's Baron Harkonnen, are set to wage war on the spice mining planet of Dune and lock horns with Paul Atreides (Timothée Chalamet).

'Dune: Part 2' will also see the likes of Rebecca Ferguson (Lady Jessica) and Zendaya (Chani) reprise their roles, and Denis recently admitted the upcoming flick will be "more challenging" than the first film.

He said: "I will say it is mostly designed. The thing that helps us right now is that it's the first time I've revisited a universe. So I'm working with the same crew, everybody knows what to do, we know what it will look like.

"The movie will be more challenging, but we know where we are stepping. And the screenplay is written. So I feel confident. Frankly, the only big unknown for me right now is the pandemic."

Denis previously revealed the sequel will build on the first movie by making "more" use of IMAX to enhance the scale of the production.

He explained: "Definitely. [Cinematographer] Greig Fraser and I, we fell in love with this format, and definitely there be — even probably more — IMAX footage in this movie. Definitely."

Meanwhile, 'Dune' writer Jon Spaihts has hinted at a third movie.

He recently said: "I ended up getting moved off of it to work, not just on 'Dune: Part 2', but to investigate other cinematic prospects in the 'Dune' universe, which we are still talking about and which, again, I’m not allowed to say very much about. But it is a very rich world in which to play, and I think it is ripe with opportunities for storytelling in every direction.”

Asked if a third film is possible, he replied: "I think that’s right. There are a few tantalising strands that lead into the future and suggest that we might not be done in this universe, despite the fact that the ending of 'Dune' as a novel, which will be the ending of the second film, is a very satisfying conclusion.”

Production is due to commence later this year, with the flick slated for release on October 20, 2023.