Mark Ruffalo is transforming.

With a string of films, from the lauded AIDS drama "The Normal Heart" to the musical rebirth tale "Begin Again" to the upcoming wrestling drama "Foxcatcher," the man many know as the Hulk has muscled together a shape-shifting string of roles.

"You push and you work hard, you stay positive and eventually all the stars sort of align," Ruffalo said in an interview. "I feel like I'm kind of in one of those moments where everything converges at one time. It's been an interesting few years for me and kind of tough, just my inner-life. I feel like I had kind of a midlife thing going on. People close to me died. It's just been a really reflective time and a growing time, so where I'm at right now feels like, 'OK, I'm coming out of the other side of that and I survived it.'"

Ruffalo has two films premiering this week at the Toronto International Film Festival: Bennett Miller's "Foxcatcher" (already a hit at Cannes) and the family drama "Infinitely Polar Bear" (already acclaimed at Sundance). The films cap a busy year for the actor, one that has already included the indie success "Begin Again," in which he plays a wayward middle-aged record executive, and the Emmy-winning HBO drama "The Normal Heart," based on Larry Kramer's play about the early years of the AIDS outbreak in New York City. He's also been shooting the "Avengers" sequel, "Age of Ultron."

Ruffalo, 46, has long been widely admired for his warm sincerity and emotional openness as an actor. He's worked steadily, mixing in character and leading parts since his breakout in Kenneth Lonergan's tender sibling drama "You Can Count on Me" (2001), including an Oscar nomination for 2010's "The Kids Are All Right." But it's been an often interrupted journey.

Shortly after "You Can Count on Me" — just as he was eagerly sought by Hollywood after 12 long years of fighting for parts — Ruffalo was diagnosed with a benign brain tumor. His face was paralyzed for a time. In 2008, his younger brother Scott was killed in Beverly Hills, a case that remains unsolved.

Ruffalo describes his recent years, which also involved struggle over balancing his work with his wife, Sunrise Coigney, and their three children, as "a roiling dis-assemblage."

"Everything was reforming," he says. "It's starting to settle."

What's striking about Ruffalo's current streak is his physical stretching, something that only begins with his Hulk morphing in "The Avengers." As a kind of stand-in for Kramer in "The Normal Heart," he plays an impassioned gay man in the early '80s. In "Foxcatcher" (due out Nov. 14), he plays Olympic wrestler Dave Schultz, a role for which he added muscle mass and grew a beard.

The transformation comes through most off the mat in Schultz's physically affectionate bearing. It's a fitting part for Ruffalo, who wrestled in high school growing up in Kenosha, Wisconsin, before dedicating himself to theater.

"I'm really getting into the physical life of a character and how it's different than me," says Ruffalo.

"To see how much he's grown and stretched himself and how many different kind of parts he's played — I'm so happy he's become so successful," says Lonergan, who essentially discovered Ruffalo, casting him in his play (currently revived on Broadway) "This Is Our Youth." ''He's very, very predictably unchanged by it and still a sweet, self-effacing person with very good values, very kind-hearted and loving. And I think that all comes out in his acting."

It was Ruffalo's Terry — aimless but loveable — in "You Can Count on Me" that made writer-director Maya Forbes want him for "Infinitely Polar Bear." Ruffalo plays a manic depressive father of two girls.

"That movie, you could draw a direct line to 'Infinitely Polar Bear,'" says Forbes. "It's the same kind of person who you care about deeply but is so flawed."

For Ruffalo, "You Can Count on Me" remains a touchstone, too.

"I feel like I'll never get back to that level of acting, in a way," he says. "I'm probably more polished as an actor and I've grown as an actor beyond that, but it's just so raw and honest-feeling. I look at that guy and I'm like, 'That guy was good.'"

But Ruffalo has expanded in many other directions, including his persistent advocacy over fracking and clean energy. He bought 27 acres (11 hectares) in New York's Catskills when he was 28, land he has since built a house on. Now, some 14 year after "You Can Count on Me," Ruffalo has grown into a fully mature, versatile actor.

"I've really committed myself in a way I really never had," says Ruffalo. "I feel like maybe I've always held back a tiny little bit because then I could always say, well, if a movie doesn't do well, if people don't appreciate what I've done, it's 'cause I didn't go all the way. I'm acutely aware that I'm getting older. I probably have another five, 10 years if I'm lucky, in front of the camera where I can still do a lot of stuff, and then I think I'll be on the downward side of it. So I want to make these last few years count."