The actor's parents were struggling Russian immigrants who came to America during the Bolshevik Revolution and settled in Brooklyn, New York, where Damon was born. As a child, Stuart loved making his family and others laugh. At age 11, he played the cowardly lion in a production of The Wizard of Oz, and later starred and sang in musical comedies at a summer camp near Danbury, Connecticut.

Stuart attended a private high school, continuing his studies at Brandeis University, where he obtained a B.A. degree in psychology. He was on his way to becoming an attorney, but got sidetracked when his involvement in acting turned into a professional pursuit. He began playing lead roles in summer stock with such stars as Jane Powell and George Gobel. In the next few years, he gained experience in more than 50 musical comedies, washing a few dishes along the way to help with finances.

He landed his first Broadway role in the chorus line of Irma La Douce, where his dance partner was Elliott Gould. He also understudied the principals, and after two weeks took over one of the leads. That break led to other Broadway shows.

In 1964, Stuart was named Most Promising Performer of the Year by Theater World for his performance in The Boys From Syracuse. The following year, he was brought to Hollywood to star with Lesley Ann Warren in the now-classic TV musical production of Rodgers and Hammerstein's Cinderella. The program attracted worldwide attention. A lucrative offer to star on an English television series, The Champions, sent Stuart to Great Britain with his British-born wife, actress Deirdre Ottewill-Damon, and their daughter, Jennifer. During the next 12 years, Stuart starred on British television and played many roles on stage in London's West End.

Shortly after returning to the United States in 1977, Stuart was signed as a series regular on General Hospital. His performance in the soap opera led to many things: A starring role in the highly rated TV suspense thriller, Fantasies; a 1981-82 ABC Monday Night Movie; a cameo in the comedy feature film, Young Doctors in Love, an ABC Motion Picture released in 1982; an appearance in Bob Fosse's Star 80; and a highly dramatic guest-star role on an episode of Arthur Hailey's Hotel on ABC.

Stuart returned to the stage in 1982 to play King Arthur, opposite his wife in the role of Queen Guenevere, in a San Diego production of Camelot. It marked the first time the two had performed together in ten years.

Early in 1988, Damon made his play-directing debut with the world premiere production of What's Wrong With This Picture?, at the Back Alley Theater in the Van Nuys area of Los Angeles.

Stuart has been active with the Juvenile Diabetes Foundation since 1983 and has been instrumental as a major fund-raiser. He also, along with co-star Leslie Charleson, is active with the Mountain AIDS Foundation of Santa Monica.

Damon has retained his love of athletics. He is a serious sports fan and an ardent golfer. Using skills developed when they renovated a 16th-century farmhouse in England, Stuart and Deirdre have since renovated a house in the Hancock Park area of Los Angeles. They have a daughter, Jennifer, and a son, Christopher; and are the beaming grandparents of Alexander Damon.