BOSTON -- His eyes, a penetrating blue, are too deeply set. His teeth are neither capped nor straightened. Topped with a thinning thatch of brown curls, his doughy face has clearly never been nipped, tucked, or Botoxed into some acceptable approximation of Hollywood hunkiness.

Actor John C. Reilly knows he doesn't have movie-star looks.

"Whenever people talk about my movie work, or the characters I play," he said with a laugh, "they always mention that I'm like a regular guy, an everyday Joe -- you know, kind of homely with a mug only a mother could love."

Reilly may not have the face of a movie star, but he has something more meaningful and lasting -- a career as a well-respected actor. For 15 years, he has captivated New York and Chicago theatre audiences in such plays as True West and has been featured in more than two dozen films, including What's Eating Gilbert Grape, Casualties of War, Boogie Nights and Magnolia.

Always familiar but never banal, Reilly has specialized in exploring the unpolished but indelible soul of the Everyman -- from the doomed Gloucester fisherman who, with his dying breath, worries about his young son in The Perfect Storm, to Jennifer Aniston's pot-smoking couch potato of a husband in The Good Girl, which is still in theatres.

By year's end, he'll also appear in three high-profile films: Martin Scorsese's epic Gangs of New York; Chicago, the film adaptation of the hit Broadway musical; and The Hours, based on Michael Cunningham's Pulitzer Prize-winning novel.

Now, Reilly is starring in Boston as perhaps the quintessential regular guy in Marty, a new musical based on Paddy Chayefsky's acclaimed teleplay of the same name, later transformed into a 1955 Academy Award-winning film starring Ernest Borgnine. In this Huntington Theatre production opening tomorrow, Reilly is Marty, a lonely 34-year-old Bronx, N.Y., butcher who lives with his mother, and in his own words, has been "looking for a girl every Saturday night of my life." Just as he becomes resigned to bachelorhood, he meets the shy Clara (played by Anne Torsiglieri) and imagines the possibility of love.

"Paddy Chayefsky said that his aim in telling this story was to tell the truth about everyday people. He wanted to immortalize everyday people, warts and all, and I really relate to that," said Reilly over a lunch-time interview.

"It tells a really universal story about lonely people looking for a connection, and it tells a story about a regular guy," he said. "The play isn't the most ironic or tongue-in-cheek. It's a real, pure, straight-ahead story that tries to capture the human condition, and I find it a really appealing, emotionally satisfying piece."

When it first aired as a live teleplay in 1953, with Rod Steiger as Marty and Nancy Marchand (best remembered as Tony's brittle mother Livia on HBO's The Sopranos)as Clara, what distinguished Marty was its realism. With its decidedly unglamorous characters, it presented a tangible slice of life. Hence, Marty would seem a strange choice for a musical.

"Always with an adaptation, you want to see what is in the story that can be sung, what is unsaid, that can be said in song," said Marty director Mark Brokaw, after a recent rehearsal. "In that way, I think this is a perfect story to adapt because it's about two people -- Marty and Clara -- who've never really been allowed to speak what's inside them. So this is a perfect vehicle for them to let out in song something about them that we wouldn't find out otherwise."

This one-act musical is based on Chayefsky's script but is not a word-for-word re-creation. The book, by Tony Award-winning playwright and composer Rupert Holmes, expands the original story, exploring more deeply the relationship between Marty and Clara. The music and lyrics, by Charles Strouse and Lee Adams (who collaborated on Bye Bye Birdie), pushes the story into "hyper-reality," Reilly said.

"The general rule about musical theatre is when you can no longer speak, you must sing, and that's the way I've tried to think of it as an actor," he said. "Marty himself doesn't sing; he's much shyer than that. But when you hear him sing in the play, it's as if it's his soul singing."

For years, Jim Weissenbach, one of this show's producers, envisioned Marty as a musical. Things seemed ready to roll with Jason Alexander of Seinfeld fame as the star, until his other commitments capsized that deal. Weissenbach heard about Reilly's interest in doing a musical, but when the actor was contacted, he wasn't sure he wanted the role.

"I love musicals, but one of the things I find really discouraging about going to see a musical on Broadway is this kind of cellophane curtain between the audience and stage with the microphones, overproduction of the sound, and the spectacle and all that," Reilly said. "So I told them the only reason for me to do it was to take down that cellophane curtain and really touch people.

"In the postmodern world we live in, there's this snarky, smart-assed attitude about musical theatre, and it's easy to joke about how corny it is," Reilly said. "But when a musical touches you, it's a way to get to people's hearts."

For most of his 37 years, acting has touched Reilly's heart. When he was 8, his best friend invited him to a drama class in a local park, and "that was it. I loved it," he said.