Eric McCormack is best known for a sitcom role (Will Truman on “Will & Grace”), but he got his start onstage, spending the first five years of his career with Canada’s Stratford Festival. His work has now spanned film (“The Lost World,” “Giant Steps”), television (from recurring roles in “The New Adventures of Old Christine” and “Dead Like Me” to starring roles in “Lonesome Dove: The Series,” “Perception” and “Travelers”) and theater (“The Music Man” on Broadway, “Some Girl(s)” Off Broadway).

He can be seen as Will Truman once again in the “Will & Grace” revival for NBC, and soon he’ll be reprising one of his beloved theater roles: in a special one-night-only engagement of “The Fantasticks.” McCormack was first mentioned in Variety on June 27, 1990, for his part in a stage version of Robin Maugham’s “The Servant.”

You were doing plays since childhood, but what do you consider the true start of your professional career?  
I was still in my last year of high school in Toronto, and I was working at a dinner theater called O’Neill’s. It was one of those shows where everybody’s waiter suddenly became the performers, and I saw the show about 80 times as I bused tables night after night. One day I was literally washing dishes, and I heard the two owners talking about the show, worried about one of the guys who was sick. I did that classic “All About Eve” with a dish in my hand and an apron on [and said], “I can do it. I know the show.” And Sandra, who ran the place, said, “Oh honey, you are so cute,” and then ignored me. But the next day I was in history class, and I got called to the office, and Sandra was on the phone. “Are you serious?” she asked. I said yes. The show was called “One Big Break,” and that was my one big break.

What made you want to focus on theater at that time?
As much as I grew up on television and film later in the ’70s, I always kind of dreamed locally. I looked around and I thought, “If I can make a living as a theater actor in Toronto, good.” And I did.

Where does “The Servant” come in?
The ’80s for me were entirely theater in Canada — particularly ’85 through ’89 with the Stratford Festival, which was Shakespeare and classics in rep, and was really amazing. “The Servant” was the following year in Toronto with Keir Dullea. That was the year before I took off for Vancouver and started focusing on television.

What made you ready to make the jump from stage to screen?
It was ’89-’90 and there was a guy who was about to take over the Stratford Festival. He had been watching me for five years, and he said, “I don’t have an offer for you for next year. Maybe it’s time for you to move on. You have a very modern sensibility; have you ever thought about television comedy?” He didn’t mean it in a nice way, but he was absolutely right. And eight years later I was playing Will Truman. So it was the beginning of me going, “Maybe it’s time to change.”

Has your theater training and background helped over the years?

There’s no question. Rachael Leigh Cook — who was on “Perception” with me for three years — one day said, “I’ve never been on a stage.” She was a young actress, and she got movie [and TV] roles. But that was so foreign to me. It was like eating dessert without eating your dinner. You have to start [onstage]. And particularly ending up on “Will & Grace”: We’ve done every show we’ve ever done in front of a live audience. All four of us [including Debra Messing, Megan Mullally and Sean Hayes] are from the theater, and I think that’s really lent itself to our style.