Patrick Duffy

Patrick Duffy (born March 17, 1949) is an American actor of stage, television and film. He is best known for his role on the CBS soap opera Dallas, where he played Bobby Ewing from 1978 to 1985 and from 1986 to 1991. Duffy returned to reprise his role as Bobby in a continuation of Dallas currently airing on TNT. He is also well known for his role on the ABC sitcom Step by Step as Frank Lambert, the husband of Carol Lambert (Suzanne Somers) from 1991 to 1998, along with his role as Stephen Logan on the CBS drama, The Bold and the Beautiful.

source: Wikipedia