The first thing you notice about Donna Murphy is that she looks nothing like Fosca, the intensely unattractive and fatally ill 19th-century woman she plays in Stephen Sondheim and James Lapine’s Passion, a portrayal for which she has received this year’s Tony Award as Best Actress in a Musical.

The show has won the Tony for Best Musical, as well as for Best Book and Score, and this day Murphy is sitting backstage at the Plymouth Theatre surrounded by the telegrams, letters, and cards from well-wishers that flank her brightly lit dressing-room mirror, talking about the character she plays, the career she has fashioned, and, first of all, the Tony she has won.

“I was kind of numb,” she says of Toni night. “I remember I stood up and kissed Dee Hoty, who is a friend and was also nominated, and I didn’t kiss my husband. I kind of sailed onstage. I felt about 10 years old. I was in a gown and had a lot of make-up on, but I felt as If I was 10 When I got to the microphone, my first impulse was to find my mom and dad in the mezzanine and let them know I knew where they were. And when I was done I thought, ‘Oh, my god, there are so many people I forgot to thank.’ You ought to win these awards when you’re six or 10 so there are only Mom and Dad to thank.”

Murphy may not have won a Tony at age six, but she admits to thinking about doing so since her childhood, first in Corona, Queens, then in Hauppauge, L.I., and finally in the small town of Topsfield, Massachusetts.

“I started watching the Tonys when I was a little girl,” she says. “My mom loved music, but my parents were not avid theatregoers. I remember once they went to see a musical, and when they came home I looked at what my mom was holding and I thought, ‘Wow, a Playbill from a Broadway show.’”

Murphy herself did not get to be part of a Broadway audience until she was a teenager, but, years earlier at age four, she asked her mother for singing lessons. “I always was a little performer,” she says. Her performing, however, came only in school and community productions. “I asked my parents to let me come to New York and audition,” she says, “but they said no. They were not turned on by the idea of my singing professionally. They were flattered and proud when my teachers told them they thought I could pursue this. But I was a good student, and they wanted that to be the priority. I think they always thought I would somehow outgrow it.”

But outgrow it she did not. Murphy ended up at New York University in the undergraduate drama program, where she studied with the legendary Stella Adler. But in her sophomore year she vegan going to open calls for Broadway musicals, and after she got a job as an understudy in They’re Playing Our Song (she eventually replaced Debbie Shapiro), she left school to pursue he career full time.

Her biggest break came in the mid 1980s, when, after understudying Cleo Laine in the Tony-winning musical Drood, she was hired to replace Betty Buckley in the title role. Then came the Off-Broadway musical Song of Singapore, where she received rave reviews as a zany jazz singer. And earlier this year she was starring in the musical Hello Again at Lincoln Center, where Sondheim and Lapine were planning a workshop of Passion. She was asked to audition for the tole of Fosca, the long-suffering, despeately lonely woman whose obsessive and overwhelming love for a handsome soldier first repels him and then transforms him. She got the part.

In preparing for the audition and during rehearsals and the long preview period, Murphy says she focused not on Fosca’s physical repellence but on “the place of loneliness from which she same, the shame in her and her pride. This woman has been completely cut off from contact with anyone who she feels she can really connect with, as much by her own choice as by the circumstances of her unhappy past, her ugliness and her illness.

“It was so immediately evocative,” she says. “I would strip away from myself whatever it is I do to make myself feel attractive. It just takes a shift of perspective for me to see what’s unattractive in me. I didn’t think about playing ugly. I thought about the illness, the shame, the loneliness, the bitterness. And that’s what I brought into the room.”

What she brought into the room worked. David Richards of The New York Times called her performance “spellbinding,” and the other critics, the audiences, and the Tony voters agreed.

Right now, she is focusing on her eight performances a week, but after Passion, she says, she would like to do “something completely different” from the deeply affecting and often somber musical that these days is so much a part of her life.

“I want to do films,” she says, “I love doing comedy. Maybe a serious play. To me, it’s all about challenge, exploring the seeds of all the different feelings inside me. We all have many different sides to ourselves. Being an actor allows me to take the germ of an idea or a sensibility and allow it to blossom into an entire character that very often seems such a departure from myself. It’s an opportunity for me to grow, to learn. Each job is a set of challenges. And that’s what keeps me interested.”