John Karlen is an American actor best known for playing Willie Loomis, Carl Collins, William H. Loomis, Desmond Collins and Kendrick Young on the ABC serial Dark Shadows, in various episodes which aired from 1966-1971.
In 1971 Karlen starred as the male lead in Daughters of Darkness. He also starred in the 1975 television film, Trilogy of Terror, and was in the movie Killer's Delight.
He appeared in the serials From These Roots, Another World, Love Is a Many Splendored Thing and Hidden Faces.
Later Karlen was Harvey Lacey on the CBS crime series Cagney & Lacey, from 1982-1988. He also appeared in Murder, She Wrote in multiple seasons.