Born in Townsend, Montana, to Terrence and Marie Duffy on the 17th March 1949. He lived in Montana until age 12, when they relocated to Seattle.
In 1974, after graduating from Cascade High School, Everett, Washington, and the University of Washington he got married and moved to New York. There he worked as a carpenter and appeared on stage (never got to Broadway, though).
In 1975 he and his wife moved to California, eventually ending up in Hollywood. In the same year Padraic Duffy, Patrick’s first son, was born. Duffy had a part in The Man From Atlantis in 1976. It was in 1978 that he took the role that would make him most famous: Bobby Ewing in Dallas.
In 1980 his second son, Conor Duffy was born. Tragedy struck in 1986 when both his parents were murdered at their home in Montana. After Dallas ended he worked on Step By Step, and now this has been cancelled he is said to be working on his TV career.