Dennis Dirk Blocker (born July 31, 1957) is an American actor and the son of actor Dan Blocker, of the popular TV series, Bonanza. Dirk Blocker began appearing in American television in 1974, acting in an episode of Marcus Welby, M.D. at the age of sixteen. He has had guest roles in ER, Little House on the Prairie, The X-Files, Beverly Hills, 90210, Walker, Texas Ranger, Murder, She Wrote, Quantum Leap and CHiPs. Blocker was a regular on Baa Baa Black Sheep as one of the main pilots.