<Li> Robert Downey Jr. as Tony Stark / Iron Man: A self - described genius, billionaire, playboy, and philanthropist with an electromechanical suit of armor of his own invention . Downey was cast as part of his four - picture deal with Marvel Studios, which includes Iron Man 2 and The Avengers . Downey said that he initially pushed Whedon to make Stark the lead: "Well, I said,' I need to be in the opening sequence . I don't know what you're thinking, but Tony needs to drive this thing .' He was like,' Okay, let's try that .' We tried it and it didn't work, because this is a different sort of thing, the story and the idea and the theme is the theme, and everybody is just an arm of the octopus ." About the character's evolution from previous films, Downey said, "In Iron Man, which was an origin story, he was his own epiphany and redemption of sorts . Iron Man 2 is all about not being an island, dealing with legacy issues and making space for others...In The Avengers, he's throwing it down with the others". </Li> <Li> Chris Evans as Steve Rogers / Captain America: A World War II veteran who was enhanced to the peak of human physicality by an experimental serum and frozen in suspended animation before waking up in the modern world . Evans was cast as part of a deal to star in three Marvel films, in addition to The Avengers . Evans said that Steve Rogers is much darker in The Avengers: "It's just about him trying to come to terms with the modern world . You've got to imagine, it's enough of a shock to accept the fact that you're in a completely different time, but everybody you know is dead . Everybody you cared about...He was a soldier, obviously, everybody he went to battle with, all of his brothers in arms, they're all dead . He's just lonely . I think in the beginning it's a fish - out - of - water scene, and it's tough . It's a tough pill for him to swallow . Then comes trying to find a balance with the modern world ." Regarding the dynamic between Rogers and Tony Stark, Evans said, "I think there's certainly a dichotomy--this kind of friction between myself and Tony Stark, they're polar opposites . One guy is flash and spotlight and smooth, and the other guy is selfless and in the shadows and kind of quiet and they have to get along . They explore that, and it's pretty fun ." </Li> <Li> Mark Ruffalo as Bruce Banner / Hulk: A genius scientist who, because of exposure to gamma radiation, transforms into a monster when enraged or agitated . Ruffalo, who was considered to play Banner in The Incredible Hulk before Edward Norton took the role, was cast after negotiations between Marvel and Norton broke down . About replacing Norton, Ruffalo said, "I'm a friend of Ed's, and yeah, that wasn't a great way for all that to go down . But the way I see it is that Ed has bequeathed this part to me . I look at it as my generation's Hamlet ." About the character, he said, "He's a guy struggling with two sides of himself--the dark and the light--and everything he does in his life is filtered through issues of control . I grew up on the Bill Bixby TV series, which I thought was a really nuanced and real human way to look at the Hulk . I like that the part has those qualities". Regarding the Hulk's place on the team, Ruffalo said, "He's like the teammate none of them are sure they want on their team . He's a loose cannon . It's like,' Just throw a grenade in the middle of the group and let's hope it turns out well!" This is the first production in which the actor playing Banner also plays the Hulk . Ruffalo told New York magazine, "I'm really excited . No one's ever played the Hulk exactly; they've always done CGI . They're going to do the Avatar stop - action, stop - motion capture . So I'll actually play the Hulk . That'll be fun". The 3D model used to create the Hulk's body was modeled after Long Island bodybuilder and male stripper Steve Romm, while the Hulk's face was modeled after Ruffalo . To create the Hulk's voice, Ruffalo's voice was blended with those of Lou Ferrigno and others; however, the Hulk's only speaking line ("Puny god .") was provided solely by Ruffalo . </Li> <Li> Chris Hemsworth as Thor: The crown prince of Asgard, based on the Norse mythological deity of the same name . Hemsworth was cast as part of a multiple movie deal . He had previously worked with Joss Whedon on The Cabin in the Woods . Hemsworth said that he was able to maintain the strength he built up for Thor by increasing his food intake, consisting of chicken breasts, fish, steak, and eggs every day . When asked exactly how much, Hemsworth said, "My body weight in protein pretty much!" He remarked that Thor's motivation "is much more of a personal one, in the sense that it's his brother that is stirring things up . Whereas everyone else, it's some bad guy who they've gotta take down . It's a different approach for me, or for Thor . He's constantly having to battle the greater good and what he should do vs. it's his little brother there...I've been frustrated with my brothers at times, or family, but I'm the only one who is allowed to be angry at them . There's a bit of that ." </Li>

Who plays the hulk in the avengers movies