Patrick G. Duffy (born March 17, 1949) is an American character actor of stage and film. He is best known for his role on the CBS television drama Dallas, where he played Bobby Ewing from 1978 to 1985 and from 1986 to 1991. He is also well known for his role on the ABC television sitcom Step by Step as Frank Lambert, the husband of Carol Lambert, played by Suzanne Somers, from 1991 to 1998..