Roberts had a genial stage personality perfect for musical comedy, and he originated roles in Broadway musicals like “How Now, Dow Jones" and “Sugar," an adaptation of the movie “Some Like It Hot."

Mr. Roberts appeared in dozens of films and Broadway shows but was best known as the unflappable counterpoint to Allen’s tightly wound characters.

He had an acclaimed Broadway career in musicals and comedies, but moviegoers knew him mostly as the self-assured, easygoing friend of Mr. Allen’s insecure heroes.