Pernell Roberts: Versatile actor best known as Adam Cartwright of 'Bonanza'

(GETTY)

Pernell Roberts, who has died aged 81, will be remembered best for playing Adam, the oldest of the three Cartwright sons on the long-running television Western, Bonanza.

The last surviving member of the cast, he was also the first to leave the programme. A talented stage actor, Roberts felt frustrated after six seasons of battling producers and writers over his character. Adam was supposedly "eastern-educated", but Roberts chafed at having to call Lorne Greene, playing the patriarch, Ben Cartwright, "Pa", especially as Greene was only 13 years his senior.

A southerner with a fierce commitment to civil rights who had taken part in the Selma march, Roberts argued over the show's proclivity for casting white actors as Indians or Orientals, while the show's one actual Oriental, Victor Sen Yung, playing the Cartwright's cook, Hop Sing, was forced toward stereotype. When he left the show Roberts called it "junk TV", and said that the network, NBC, was "perpetuating banality".

Pernell Elvin Roberts Jr. was born in May 1928 in Waycross, Georgia, where he sang and played multiple instruments. He dropped out of college at Georgia Tech to join the Marines, where he played in the band. He then attended the University of Maryland, but again dropped out and began acting, eventually performing in classic theatre with Washington's Arena Stage company. In 1955 he won a Drama Desk Award for his energetic performance in Macbeth for the American Shakespeare Festival; the next year he played on Broadway in The Lovers with Joanne Woodward.

After three starring roles in 1957, he moved to Hollywood, making his television debut in Whirlybirds, about helicopter-based cops, and a showy role as a French trapper in Northwest Passage. But Westerns were American television's favourite programmes, and Roberts became a popular guest-star on shows like Sugarfoot, Tombstone Territory and Have Gun – Will Travel, where his part as an exploiter of Chinese coolies prefigured his protests on Bonanza.

His rich voice saw him feature in four fairy-tale episodes of Shirley Temple's Storybook, and he played in Much Ado About Nothing in the live-broadcast Matinee Theatre. Roberts made his film debut in the 1958 adaptation of Eugene O'Neill's Desire under the Elms, with Burl Ives, Sophia Loren and Anthony Perkins, whose painstaking method-acting drove Roberts to ill-expressed distraction.

But if Roberts felt typecast by Westerns, they also provided his finest role, in Ride Lonesome (1959), arguably the greatest of the B-movies starring Randolph Scott and directed by Budd Boetticher. Roberts recognised the film's classic structure; his engaging outlaw, Sam Boone, counterpoints Scott's granite-faced Ben Brigade, maintaining the tension of whether they will work together or clash. He similarly played off James Coburn, making his film debut as Boone's quiet sidekick, Whit.

Roberts joined Bonanza soon after, leaving in 1965 after 202 episodes, and after making one album as a folk singer and another with the Bonanza cast. For all his desire to play better parts, his first role after leaving Bonanza was in The Girl from U.N.C.L.E. He was soon busy again with Westerns, including the only one that ran for longer than Bonanza, Gunsmoke, and the Bonanza-copy The Big Valley, although for the next 15 years he worked across the spectrum of TV.

His film career floundered, however, after a series of low-budget movies with the veteran TV director John Peyser, including Tibetana (1970) Four Rode Out (1970) and The Centerfold Girls (1974). But steady television work allowed Roberts to return to the theatre. He played Rhett Butler in the ill-conceived Scarlett opposite Lesley Ann Warren, but had more success in a 1972 revival of Captain Brassbound's Conversion with Ingrid Bergman. He travelled frequently in popular musicals like The King and I and Camelot.

In 1979 he began a seven-year run starring in Trapper John, MD, reprising the MASH character played by Donald Sutherland in the film and Wayne Rogers in the TV version. The show allowed Roberts to both use his dramatic range and address issues. After Trapper John he hosted the short-lived series FBI: The Untold Story. In 1991 he made one more, elegiac appearance in a Western, playing a Tom Horn figure in The Young Riders, and his last role on television came in a 1997 episode of Diagnosis Murder.

Roberts died of pancreatic cancer, at home in Malibu on 24 January. He is survived by his fourth wife, Eleanor Criswell; three previous marriages ended in divorce. His son, Jonathan, by his first marriage to Vera Mowry, died in a motorcycle crash in 1989.

Michael Carlson

Pernell Elvin Roberts, Jr., actor: born Waycross, Georgia 18 May 1928; married four times (one son, deceased); died Malibu, California 24 January 2010.