Described by Leonard Maltin as the "quintessential New Yorker or cranky straight man", Kirby appeared in a series of comedies, typically playing fast-talking, belligerent, yet likable, characters. His best-known roles include a colleague of Albert Brooks' film editor in "Modern Romance"; a talkative limo driver in "This Is Spinal Tap"; the jealous, comedically impaired Lt. Hauk in "Good Morning, Vietnam"; and a shifty assistant to Marlon Brando—a parody of his "Godfather" role—in "The Freshman". Kirby balanced comedies with dramatic roles like "Donnie Brasco" as a double-dealing mobster.