Actor Peter Facinelli is stubborn, especially when it comes to his work. When he was just starting out he refused to play any Italian-American roles, though his parents are from Italy.

“I said, ‘No, I don’t want to do that, because with the last name Facinelli, that’s all I’ll do for the rest of my life.’ So there were roles I would just say, ‘No! I don’t want to do that. Let me go play the Irish kid.’ ”

For a beginning actor, that stand proved a sizable risk. “It’s a lot easier if you do one thing well,” he admitted. “They know where to put you. When you’re always having to prove yourself, that you can do something — it’s, ‘Well, I’ve never seen him do it. I don’t know.’ But that’s why I WANT to do it.”

Now Facinelli is playing two physicians: the kindly vampire doctor in the “Twilight” saga — “New Moon,” the second in the series, opened Friday—and the cocky Dr. Cooper on Showtime’s “Nurse Jackie.”

Facinelli isn’t worried he might be typecast by playing two doctors simultaneously. “I don’t really play the occupation. I play the person. They both wear a lab coat. But the people in those lab coats are so dynamically different,” he said.

“They’re 180 degrees, a world apart. So it’s fun to be able to play characters of the same occupation. There are people when they meet me know me from ‘Nurse Jackie’ and don’t even realize I’m in the ‘Twilight’ series. When I look back on my years, the fun part of the things I’ve done is that everything’s a little bit different.”

He’s always been true to his conviction. He’s played characters as diverse as a blind mountain climber, a slick cop, a loopy art student — even Jesus. “And when you stack up the characters I’ve done, the character from ‘Damages,’ Dr. Cooper from ‘Nurse Jackie’ and Dr. Carlisle from ‘Twilight,’ they’re all different. And for me as an actor, that’s what makes it fun to do what I do.”

Facinelli recalls he first got the idea of acting when he was in the third grade. “There was a picture biography book on Robert Redford, and I was looking at this little biography book and all the films that he had made. I remember thinking, ‘That’s interesting, an interesting career.’ Then I saw ‘Butch Cassidy and the Sundance Kid’ when I was a little bit older and remember seeing Paul Newman and Robert Redford having so much fun on screen. I thought, ‘That’s what I want to do.’ ”

But he was so shy, his parents didn’t take him seriously. “My family kind of laughed it off because they didn’t think it was possible. For a long time I didn’t do anything about it. But when I got to college I realized, ‘I just don’t think I’m going to be happy doing anything else.’ So I transferred to [New York University from St. John’s University] and studied theater there.”

Facinelli, 35, is married to actress Jennie Garth, and they are the parents of three little girls, 1, 3 and 6. “Jen and I have been together since ’95, so it’s 14 years, almost like a million years in Hollywood.”