On Broadway, Mars appeared in The Affair, Any Wednesday, and The Best Laid Plans.
His film credits include iconic roles in two Mel Brooks' movies: Young Frankenstein, in which he played Inspector Kemp, and The Producers, in which he originated the role of Nazi playwright Franz Liebkind. Among his many other films are What's Up Doc?, Radio Days, Shadows and Fog, and Desperate Characters.
In addition, he had recurring roles on such television series as Malcolm in the Middle, Fernwood Tonight, and America Tonight.
He is survived by two daughters, as well as six grandchildren.