LOS ANGELES - Don't let Mark Ruffalo's serene demeanor fool you. He admits there's a bit of an Incredible Hulk temper lurking underneath.
Ruffalo, who comes off as a guy who could give Clark Kent a serious challenge in the mild-mannered department, plays brilliant scientist Bruce Banner - and his big, green alter ego, the Hulk - in the superhero tale "The Avengers," opening Friday in the U.S.
The actor said there was a time when he had anger issues.
"When I was a young actor, if you came to my apartment, you would have seen pictures and photos hung in the most bizarre places, where they were covering holes in the wall from auditions that I didn't get or slights that I felt I had suffered, where things were thrown, cups were thrown at the walls," Ruffalo said. "I'm no stranger to that kind of anger and rage.
"But over time, I've, like a rock that's spent many times being tumbled around in the sea, I've sort of gotten the edges polished off of me. I'm not fighting the same fights that I was back then, the same demons."
An Academy Awards nominee for 2010's "The Kids Are All Right," the 44-year-old Ruffalo has built an impressive list of credits in independent and studio films, including "You Can Count on Me," "Shutter Island," "Zodiac" and "Eternal Sunshine of the Spotless Mind."
He never saw himself as superhero material, let alone the Hulk, considering the Marvel Comics character had been played by Eric Bana then Edward Norton in two big-screen films over the last decade that failed to please fans.
The nice thing with "The Avengers" is the Hulk doesn't have to carry the film. Banner's a reluctant recruit to the superhero dream team. That allowed writer-director Joss Whedon to hold Banner back, pick up the man's trail after he had found some sense of shaky equanimity through which he keeps the "other guy," the Hulk, from breaking forth.
It lends more emotional power to the Hulk when he's eventually unleashed. And through motion-capture technology in which Ruffalo's body language and performance is digitally captured as the undercarriage for the Hulk, topped off by computer animation, the green giant looks more genuine and moves more credibly among real people than he did in the earlier movies.
The Hulk's face even resembles Ruffalo's - tinted green and strained and bloated in colossal rage.
"It's creepy, I have to say," Ruffalo said as he looked through a photo album with stills of him transformed into the Hulk. "It's exactly what we wanted it to be like. Even my chest hair, the gray in my hair. Wow. It's pretty amazing, but it's a little shocking."
With the foundation Ruffalo has built in "The Avengers," Whedon said he would love to see him in a solo Hulk movie.
Hollywood might be reluctant to go there again, but Ruffalo said he would be game, and plenty of fans seem to like the idea.
"I haven't heard any talk about it from the producing side of the table, but people have been tweeting it. There's been a campaign growing. I would be into doing it, I would think, if we could come up with the right story line," Ruffalo said. "And if they want to see a 50-year-old Hulk. That might be the big thing. No one might want to see me doing this again."