In 1958, Roberts guest-starred as Captain Jacques Chavez on the NBC adventure series Northwest Passage based on the life of Major Robert Rogers in the French and Indian War. He appeared with fellow guest star Fay Spain in the 1958 episode "Pick up the Gun" of Tombstone Territory. In 1958 he played the lead villain in the 31st episode of Have Gun - Will Travel, portraying a killer boss exploiter of Chinese Coolie laborers entitled "Hey Boy's Revenge." The episode drew critical acclaim for shedding some light on the contribution of indentured Chinese workers in building the U.S. west and for also carrying a socially conscious message "white man's laws can deliver justice for a minority" a "Paladin Parable" so typical of the series. In 1959, he co-starred in the film Ride Lonesome.
He came to prominence playing Ben Cartwright's urbane eldest son, Adam, in the Western television series Bonanza. Despite the show’s success, he left after the sixth season in 1965 due to disagreements with the writers and a desire to return to legitimate theatre. Among other complaints, Roberts argued that a 34-year-old, educated, Eastern-born man would not be calling his father "Pa". The writers tacitly agreed not to exceed three "Pa" references per episode.
I had six seasons of playing the eldest son on Bonanza. Six seasons of feeling like a damned idiot, going around -- me, like a middle-aged teenager, saying, "Yes, Pa," "No, Pa" on cue. It was downright disgusting -- such dialogue for a grown man. I felt I wasn't being taken seriously as an actor, and that's like death to one's talent...Stuck as Adam Cartwright, I was only able to use about one-tenth of my ability.
Roberts continued to do guest shots on TV shows such as The Big Valley, Mission: Impossible, The Wild Wild West, Gunsmoke, Mannix, The Odd Couple, Hawaii Five-O, and The Hardy Boys. His rich baritone voice was displayed when he played Jigger in an ABC television presentation of Carousel and Rhett Butler in the Los Angeles stage production of Scarlett.
He regained star status in the early 1980s while starring in the television series Trapper John, M.D. (1979-86). Roberts played the character almost twice as long as Wayne Rogers did (1972–1975) on the CBS M*A*S*H series.
In 1988, Roberts co-starred with Milla Jovovich in the TV movie The Night Train to Kathmandu. A guest appearance as Hezekiah Horn in the Young Riders episode "Requiem for a Hero" won a Western Heritage Award for Roberts in 1991. In the 1980s/90s, playing off his Trapper John M.D. persona, Roberts was a TV spokesman for Ecotrin, a brand of analgesic tablets. He made his last TV appearance in 2001 on an episode of Diagnosis Murder, updating a Mannix character he had portrayed decades before.
Roberts married four times. His first marriage was in 1951 to Vera Mowry, a professor at Washington State University, with whom he had his only child (Jonathan Christopher Roberts); they later divorced. He married Judith Anna LeBreque on October 15, 1962; they divorced in 1971. His third marriage was to Kara Knack, whom he married in 1972; they divorced in 1996. He was married to Eleanor Criswell at the time of his death. Jonathan Roberts died in a motorcycle accident in 1989 at age 38.
Good Night Mr. Roberts