Donny Most was born on August 8, 1953 in Brooklyn, New York.  He developed an interest in acting after he saw a movie by the name of "The Jolson Story."  He liked the movie so much that he saw it over 50 times.  He got his first acting start at the age of 15 when he started performing at resorts in New York's Catskill Mountains.

It was in high school that he started taking professional acting classes and getting roles in television commercials.  His major television breaks were small parts on "Emergency" and on "Room 222".

He got his big break when he landed the role of Ralph Malph on the hit television series, "Happy Days."  He originally auditioned for the part of Potsie on "Happy Days," but was ruled out because of his hair color.  Ron Howard already had red hair so they did not want his best friend to also have red hair.

In 1980, Most left the "Happy Days' series to expand his acting career.  He felt that the scripts were not going anywhere and he wanted to do more as an actor.  In 1983, he played the voice of Eric in the "Dungeons and Dragons" animated series.  He did various small parts in television shows such as CHiPs, Murder She Wrote, Sliders, Baywatch and Dark Skies.

In 1993, he appeared in the movie "Acting on Impulse," and also joined a touring company of "Grease" playing the role of disc jockey Vince Fontaine.

It was during the filming of a Happy Days episode that he met his wife. Morgan Hart, in 1982 and they currently have two children.