Donny Most was born on August 8, 1959 in the Flatbush section of Brooklyn, New York. His father was an accountant. He developed his love of acting in the third grade after he saw "The Jolson Story." A local television station was running the movie several times a day and Most was mesmerized by the story of Al Jolson. In 1979, he told a TV Guide reporter that he watched the movie a staggering 50 times and memorized every line of dialogue. At the age of 15, he got his first real taste of show business by performing at resorts in New York's Catskill Mountains. He was part of a group of teenagers who played the so-called "Borscht-Belt" circuit. While still in high school, he began to take professional acting classes and appear in television commercials.
Most graduated from Brooklyn's Erasmus Hall High School, which also gave the world Barbra Streisand and Eli Wallach. He continued his education at Lehigh University in Pennsylvania and decided to spend the summer before his senior year in Los Angeles. During these few months, he won a bit part on "Emergency" and on "Room 222" and decided not to return to college.
Most's third job in television was the charm. He auditioned for the part of Potsie on "Happy Days," but was immediately ruled out because of his hair color. Ron Howard, a redhead, had already been cast in the lead role and the producers did not want another redhead to play the best friend.
But the producers liked Most too much to simply ignore him. In the original script, the character Ralph Malph was a football jock. Garry Marshall decided to cast Most as Ralph and, playing off Most's comic ability, he changed the dumb jock into the class comedian.
In 1980, Most left the series to expand his acting career. His biggest post-"Happy Days" job was doing voiceovers for the animated series "Dungeons and Dragons" (1983-86). He also made guest appearances on "Fantasy Island," "CHiPs," "Love Boat," and "Murder, She Wrote." In 1995, he played disc jockey Vince Fontaine in a travelling production of "Grease."
Like other "Happy Days" cast members, Most has become a director, working on numerous stage productions in the Los Angeles area.