<Li> Idris Elba as Heimdall: The all - seeing, all - hearing Asgardian sentry of the Bifröst Bridge, based on the mythological deity of the same name . </Li> <Li> Stellan Skarsgård as Erik Selvig: An astrophysicist and a friend of Thor . Skarsgård said he was originally not supposed to appear in the film, but received a call because "they'd written a couple of scenes, and I went and did them," not knowing if the scenes would appear in the final cut of the film . </Li> <Li> James Spader as Ultron: An artificial intelligence repurposed by Tony Stark and Bruce Banner for a pilot peace program that is overwhelmed with a god complex, and now desires to pacify the Earth by eradicating humanity . Director Joss Whedon stated that Spader was his "first and only choice" for the role, because of his "hypnotic voice that can be eerily calm and compelling" while also being very human and humorous . Feige clarified that Spader's face and body were motion captured "to create a whole performance...We did not hire James Spader to do a robot voice ." Extensive scans were taken of Spader's head and body in preparation for the role . About the character Whedon said, "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 ." Whedon added that Ultron is "not a creature of logic--he's a robot who's genuinely disturbed . We're finding out what makes him menacing and at the same time endearing and funny and strange and unexpected, and everything a robot never is ." Whedon compared Ultron to Frankenstein's monster, saying, "It's our new Frankenstein myth (...) We create something in our own image and the thing turns on us . It has that pain of' Well, why was I made? I want to kill Daddy ."' Spader called the character "self - absorbed" and added, "I think he sees the Avengers as being part of a problem, a more comprehensive problem in the world . He sees the world from a very strange, (biblical) point of view because he's brand new, he's very young...He's immature, and yet has knowledge of comprehensive, broad history and precedent, and he has created in a very short period of time a rather skewed worldview ." Spader elaborates, "He truly is an artificial intelligence with absolutely no censorship at all, no parameters really...he's got too much power, too much strength and speed and size, so he's a very dangerous child ." </Li> <Li> Samuel L. Jackson as Nick Fury: The former director of S.H.I.E.L.D. who originally recruited the Avengers and continues to be a mentor and leader for the team . Jackson described the role as a cameo, saying, "I'm just kind of passing by there...Because, it's another one of those' people who have powers fighting people who have powers' . That's why I didn't get to New York in The Avengers . There's not a lot I could do except shoot a gun ." </Li>

Who does the voice of ultron in the avengers