"Big Joe" Roberts, as he was known in vaudeville, toured the country with his first wife, Lillian Stuart Roberts as part of a rowdy act known as Roberts, Hays, and Roberts. Their signature routine was called "The Cowboy, the Swell and the Lady." At this time, in the first decade of the twentieth century, Buster Keaton's father, Joe Keaton, had started a summer Actors' Colony for vaudevillians between Lake Michigan and Muskegon Lake in Michigan. Roberts became acquainted with the Keaton family as a member of this community.
When Buster Keaton's film apprenticeship years with Roscoe "Fatty" Arbuckle came to an end, and Keaton began making his own shorts in 1920, he asked Roberts to join him. Roberts' hefty 6'3" frame, usually playing a menacing heavy or authority figure, made a striking and amusing contrast to the thin, 5'6" Keaton.
IMDB shows that Roberts made only two films without Keaton. He played the role of "Roaring Bill" Rivers in 1922's The Primitive Lover starring Constance Talmadge￢ﾀﾔKeaton's sister-in-law￢ﾀﾔand the silent film actor Harrison Ford; and a drill master in the Clyde Cook comedy The Misfit, released in March 1924, after Roberts' death.
When Keaton began making feature films in 1923, he apparently intended to continue working with Roberts. Roberts had roles in Keaton's Three Ages and Our Hospitality (both 1923). During the filming of the second feature, Roberts had a stroke but insisted on returning to the set to finish the film. After completion, Roberts suffered another stroke and died shortly afterwards.