In 1973, while under contract to Universal Studios, Farrell starred with Robert Foxworth in The Questor Tapes.During the years under contract, he guest starred in a number of shows, including Banacek, Mannix, Marcus Welby, M.In 1985, Farrell was in Central America, helping refugees from the civil war in El Salvador.A guerrilla commander, Nidia Diaz, had been taken prisoner." on I Dream of Jeannie; and an Army doctor in the episode "The Bankroll" of Combat!In 1968, he originated the continuing role of Scott Banning in the NBC soap opera Days of Our Lives.In 2014 he was a supporting cast member on the Sundance TV Network criminal drama series The Red Road.
Tomei's character died during the first episode of the series, but continued to appear as a ghost/memory in vignettes of later episodes. Even before he was well-known, Farrell was an activist for many political and social causes.
Farrell voiced Jonathan Kent in the Superman (1996) animated series, with wife Shelley Fabares voicing Martha Kent.
Farrell hosted several "National Geographic Presents" specials, and starred in a number of TV movies, including Memorial Day (which he co-produced); Sex and the Single Parent; Prime Suspect; Choices of the Heart; Private Sessions; Vanishing Act; A Deadly Silence; The Price of the Bride; Incident at Dark River; The Whereabouts of Jenny; and Silent Motive. Farrell and Minoff executive produced two feature films during their partnership, Dominick and Eugene, a 1988 Orion Pictures film which earned actor Tom Hulce a Golden Globe nomination for best actor.
He was seen in the season 10 episode "Persona" of Law & Order: Special Victims Unit.
He appeared as the character Fred Jones in the season 8 episode "Hunteri Heroici" of Supernatural.