The sum of his parts

MAYBE it’s just jealousy, but Mark Ruffalo’s buddies tease him like he’s a kid who suddenly caught the eye of all the popular girls in town. Since getting his big break opposite Laura Linney in “You Can Count on Me” in 2000, the 37-year-old darkly handsome actor has built an impressive list of movie performances as the sizzling love interest of some of Hollywood’s hottest actresses.

Consider: He’s had steamy sex scenes in movies with Meg Ryan and Naomi Watts. He charmed Gwyneth Paltrow in “View From the Top” and was madly in love with Jennifer Garner in “13 Going on 30.”

He’s starring in a romantic comedy this fall with Reese Witherspoon. (The movie, “Just Like Heaven,” opens in theaters on Friday.) And he plays Jennifer Aniston’s boyfriend in “Rumor Has It,” a loose sequel to the 1967 classic “The Graduate.” (It’s due out in December.)

So what’s the problem?

“My friends are like, ‘Dude, you are getting to be an accessory to all these actresses,’ ” Ruffalo said. He picks at a plate of French fries at Victor’s Deli in Hollywood and adds: “They’re like, ‘Don’t be an accessory.’ I tell them I’m not. These are parts. I’ve got great parts in all these movies.”

If he’s popular with the A-list actresses, it’s for a reason: Ruffalo is considered one of the best character actors of his generation. With dark eyes and curly brown hair, he oozes testosterone like a young Marlon Brando. And if his press is any indication of his sex appeal, he’s dazzled plenty of reporters in the last few years. “I really love him. Oh dear,” penned a writer for Jane magazine in 2003. British Elle bluntly called him “Mr. Lover Man.” (The declaration is understandable, considering his performance as the intense, whispery homicide detective who seduces Ryan’s character in Jane Campion’s 2003 erotic thriller “In the Cut.”)

But his friends have a point. Ruffalo has labored, albeit impressively, in the shadow of big-name actresses -- and actors -- for five years. (He played the LAPD officer in pursuit of Tom Cruise’s hit-man character in “Collateral” and the quirky scientist opposite Jim Carrey in “Eternal Sunshine of the Spotless Mind.”)

Finally, though, with four more movies in various stages of production, Ruffalo is finding his own place in the spotlight. He is becoming one of Hollywood’s most sought-after leading men.

This month, Ruffalo will begin production on “Zodiac” with Jake Gyllenhaal, Robert Downey Jr. and Gary Oldman. In the film, based on a true story, he plays the San Francisco homicide detective who tracked and nearly caught the serial killer who terrorized the city during the 1960s and 1970s.

Straight outta Wisconsin

AS he talks about his career over this late-afternoon lunch, he leans forward and holds eye contact, like he cares deeply about the conversation. There’s a sweetness about him. He sips his drink (iced tea mixed with lemonade), fiddles with his straw, picks at the leaves of a withering spider plant in a pot next to the booth, runs his fingers through his hair. The edges of his sad brown eyes slant downward, like he’s carrying some deep, secret hurt.

A native of Wisconsin, he moved to Los Angeles in the late 1980s to attend the Stella Adler acting academy. He spent years performing in theaters around town and working odd jobs to make ends meet. He said he vowed not to quit.

“I was really on a crash course with depression and did not know what I was going to do with my life, when I decided to come to Los Angeles,” Ruffalo said.

He fell in love with acting “the minute I sat in one class at Stella Adler,” he said. It gave him a chance to step out of himself.

“You can’t dwell on the past or the future, but you really have to be in the moment, and that’s addictive. I love people. I love looking at how relationships work and how vulnerable people are. Sometimes they’re not vulnerable enough, and that’s a drag. It’s like putting together a puzzle that you never really finish.”

He knew there was no turning back. “I said, ‘This is it. This is going to be my life.’ I didn’t know where acting was going to lead at the time. I just knew that I loved it. In class, they were talking about all these ideas and literature and what acting is and the responsibility socially of being an actor.”

Ruffalo said he was enthralled by what he was learning.

“They were talking about all the great writers and what they were after and how they were lifting up humanity,” he said. “You never heard anybody talk about that in pop culture. It was music to my ears as a young man. It was everything I wanted to hear ... to have meaning, to be useful.”

He relied on his idealistic view of the profession to get through the hard times.

Over the course of eight years, Ruffalo went to more than 800 auditions. The rejection was constant. “I heard a lot of ‘No.’ ‘No.’ ‘No.’ ‘No.’ ‘Nope.’ ‘No,’ ” he said. Then finally, “Yes.”

In 1997, he was cast as a nihilistic brat in Kenneth Lonergan’s off-Broadway play “This Is Our Youth.” He received rave reviews, with Variety calling his performance “funny and heartbreaking at once.”

He followed up with his role as Terry, a sweet but aimless slacker in Lonergan’s “You Can Count on Me.” (The film tied with “Girlfight” for the Grand Jury Prize at the 2000 Sundance Film Festival.)

The intermission

THEN a setback: Ruffalo was diagnosed as having a benign brain tumor. He broke the news to his wife just days after they had their first child.

He was set to appear opposite Mel Gibson in “Signs” but had to give up the part to undergo surgery. He went through months of recovery and then went back to work.

By 2003, Ruffalo was appearing in movies in quick succession, including a role as an adulterous husband -- opposite Watts and Laura Dern -- in the powerfully haunting movie “We Don’t Live Here Anymore.”

He said he prefers roles where the characters are “honestly flawed.” “I’m really a character actor,” he said. “How do you stay true to that? You have to do things for the right reasons. For everyone it’s different. For me, I always look at a part and say, is this something that interests or challenges me?”

It was his wife, jewelry store owner Sunrise Coigney, who urged him to try romantic comedy. “It’s just a genre that I don’t think is very romantic or very funny,” Ruffalo said. “It’s a tough genre, but when pulled off well, it’s pretty good. I was scared of it, and I’ve always used that as a good barometer of places to go next, sort of like making fear your friend.”

In the movie with Witherspoon, Ruffalo plays a man who falls in love with the spirit of a woman whose apartment he rents. He said he took a lot of leads from the more comical Witherspoon.

(The actress praised Ruffalo to reporters recently. “I haven’t had to work so closely with one actor before, so that’s been sort of a different dynamic for both of us, I think,” Witherspoon said. “But it’s been really good.”)

Ruffalo called the movie -- and this new phase of his career -- an “interesting turn.”

“I’m sick of hearing people say that I can’t do comedy, or I can’t do a leading man. You know?” he said. “I like the challenge.

“I want to look back on my career and say I did a lot of stuff that no one expected of me, that I tried to break whatever boundaries people set for me.”