Colvin was born in Lyndon, Kansas, twenty-seven miles south of Topeka. He began his stage career as a child performer. At the age of seventeen Colvin became a private student of Michael Chekhov. Although he appeared in hundreds of films and television shows, he always returned to the theatre. His stage roles include Marchbanks in Shaw’s Candida, Mercutio in Romeo and Juliet, Morgan Evans in The Corn is Green, Algernon in The Importance of Being Earnest, Constantin in The Seagull, and Edmund in Long Day’s Journey into Night. His film credits include Viva Max! (1969), Jeremiah Johnson (1972), Hickey & Boggs (1972), The Life and Times of Judge Roy Bean (1972), Scorpio (1973), The Stone Killer (1973), The Terminal Man (1974), Rooster Cogburn (1975), Embryo (1976) and Child’s Play (1988) among others. His partnership with Yvonne Wilder in one of the most successful comedy acts of the 1960s, Colvin and Wilder, led him to appear all over the U.S. on stage and on television, including The Dean Martin Show, The Ed Sullivan Show and The Tonight Show Starring Johnny Carson, culminating in their farewell appearance at Carnegie Hall in New York. Other television roles were on such programs as Switch, The Rockford Files, The Six Million Dollar Man, Kojak, and The Bionic Woman. While under contract to Universal Pictures for seven years, he appeared in over one hundred hours of television programming.

Colvin has won Los Angeles’ Drama-Logue Awards in five separate categories, as actor, director, playwright, producer and production designer. He taught at the central Experimental Film School of Rome, the University of Southern California, Cal State Northridge, the American Academy of Dramatic Arts, the 1994 Michael Chekhov International Workshop in Sussex, the Centre for Performance Research at the University of Birmingham in 1999, and The Michael Chekhov Association’s NYU June Intensive in 2004. His pupils included several stars whose subsequent performances that have won Academy Awards, Emmy Awards and Tony Awards. Colvin served as the Artistic Director of the Michael Chekhov Studio USA West, a position he founded, until his death from complications of a stroke.