Robert Downey Jr. "struts around" at home when he's playing Iron Man in a movie.

The actor has reprised his role as the iconic superhero for the new release Avengers Assemble, which also stars Scarlett Johansson, Samuel L. Jackson and Chris Hemsworth.

Robert's wife Susan isn't a big fan of Tony Stark/Iron Man, revealing he is her "least favourite" of the actor's famous roles.

"When I'm playing Sherlock, she'll tell me, 'I'd ask you a question but I know you already have the answer to any and all questions because you're Sherlock,'" Robert explained at the Los Angeles premiere of Avengers Assemble yesterday. "With Tony I just strut around a little more."

Mark Ruffalo also appears in the release, portraying famed green hard man The Hulk. He was delighted to be involved with the collaborative movie because it meant teaming up with so many other big name stars.

"I think part of the reason why it's so fun to watch is 'cause we're having a great time making it," he enthused.

Chris was equally as pleased with the movie, although filming some scenes was a different matter. He beefed up so much that when he tried on his Thor costume it was too tight, making it uncomfortable.

Scarlett had equal misgivings about the tight outfit she donned to portray Black Widow.

"It was fantastic," she laughed. "There's nothing as exciting as zipping yourself into a latex cat suit every day."