James Spader has been cast in 'The Avengers: Age of Ultron'.

The 53-year-old actor has been signed up to play the titular villain Ultron - a crazed robot who develops a god complex and wants to destroy all of humanity with his incredible powers - in the Marvel movie directed by Joss Whedon.

The upcoming film will see the superhero team of Iron Man, Captain America, Hulk, Nick Fury and Thor team up against the mighty Ultron, who Whedon previously said is ''not a happy guy'' as they attempt to take down the super villain.

He said: ''I knew right away what I wanted to do with him. He's always trying to destroy the Avengers, goddamn it, he's got a bee in his bonnet.

''He's not a happy guy, which means he's an interesting guy. He's got pain. And the way that manifests is not going to be standard robot stuff.''

Meanwhile, Elizabeth Olsen is being lined up to play Scarlet Witch after 'The Host' star Saoirse Ronan reportedly turned down the part.

'Kick-Ass 2' star Aaron Taylor-Johnson is in talks to play Olsen's speedy superhero sibling, and should they both sign on, it would mean a big screen reunion for the duo after recently filming Gareth Edwards' 'Godzilla' reboot together.

The new characters will join returning cast members including Robert Downey Jr. as Iron Man, Chris Hemsworth as Thor, Chris Evans as Captain America and Mark Ruffalo as the Hulk.

Additionally, Scarlett Johansson is expected to reprise her role as Black Widow/Natasha Romanoff and Samuel L. Jackson will return as Nick Fury.

'The Avengers: Age of Ultron' is set for release in 2015.