The Canadian-born Mr. Bain was an ordinary-looking man and tended to play ordinary people. As Bea Arthur's conservative, but well-meaning neighbor Arthur Harmon in the 1970s series "Maude," he indeed seemed like the sort of everyman you might end up with as a neighbor. His environs were a bit more rarified in "Diff'rent Strokes," which became a hit in 1978 on the strength of the magnetism of child star Gary Coleman. Mr. Bain played the kind, mild-mannered Mr. Drummond, a rich Park Avenue businessman who adopted the kids played by Coleman and Todd Bridges.

Born in Lethbridge, Alberta, Canada, on Feb. 4, 1923, he studied acting at the Banff School of Fine Arts. Following service in the Canadian Army during WWII, he studied at the American Academy of Dramatic Arts in New York. He became a citizen of the United States in 1946.

Following work at the Stratford Shakespeare Festival in Canada, he won the choice role of Larry Slade in the famous 1956 Off-Broadway revival of Eugene O'Neill's The Iceman Cometh. He was soon on Broadway, in a short-lived play called Sixth Finger in a Five Finger Glove. He played a variety of roles in the original, ill-fated, 1957 Broadway production of Leonard Bernstein's musical Candide.

Other Broadway credits included Makropoulos Street, The Family Reunion, Advise and Consent, Hot Spot, The Cuban Thing, An Enemy of the People and Twigs. His success on television kept him away from the stage for most of the 1970s and '80. But he returned to Broadway in 1991 in a revival of Paul Obsorn's On Borrowed Time, opposite George C. Scott. As often happened, he played a doctor.

He found somewhat better acting opportunities Off-Broadway, getting regularly cast in many of the challenging stage works of the crowded the '60s New York stage. He was in the original stagings of two noted, and slightly controversial, Bruce Jay Friedman plays, Scuba Duba (1967) and Steambath (1970). He was a member of the cast of Arnold Wesker's The Kitchen (1966), and of the American Place Theatre's hit production of William Alfred's Hogan's Goat (1965). He also performed in plays by Jack Gelber and Ugo Betti. An early, cultish credit came when he played hotel clerk Mr. Wells on the last '60s series "Dark Shadows."

As an activist for his profession, Mr. Bain played a critical role as one of the organizers of the Actors Federal Credit Union, a cooperatively run, not-for-profit financial institution, owned and controlled by its members. "It was at a meeting of the Actors Equity [Association]," he recalled, "where a member stood up and asked why we didn't do something about actors not being able to get any credit, much less a mortgage or anything like that. Someone else stood up and echoed what the first member said, pointing out that the issue really was one of equity and actors didn't have any when it came to the banks."

Bain served as the Credit Union's first president.

He is survived by three sons and one daughter. His wife, Monica Sloan, died in 2009.