The Georgia native, who played Adam Cartwright in Bonanza, started his acting career onstage in New York.
He moved to Hollywood and kicked off a film career opposite Sophia Loren in Desire Under The Elms in 1958.
But Roberts really made his name on TV, appearing in hit shows like The Rockford Files, The Streets of San Francisco, Baretta, The Six Million Dollar Man, Cannon, Ironside and Mission: Impossible.
He was in Bonanza from 1959 to 1965, and he started portraying Dr. 'Trapper' John McIntyre from 1979.
His life was marred by tragedy when his only son, Chris, was killed in a motorcycle crash in 1989.