David Bruce Cassidy (born April 12, 1950) is an American actor, singer, songwriter and guitarist. David is the only son of Jack Cassidy, a broadway actor of note from the 1950's and 1960's and his first wife Evelyn Ward. He is the older half brother of Jack and his second wife Shirley Jones sons Shaun, Patrick and Ryan. Cassidy is perhaps best known for his role as Shirley Jones' eldest son, Keith Partridge, on the popular 1970s musical/situation comedy, The Partridge Family. The show as on the air from 1970 to 1974.