He acted in many television programs, including a notable recurring role in Seinfeld as Jack Klompus, starred in Law & Order, and as Grandpa in a 1996 TV-movie revival of The Munsters' Scary Little Christmas. His appearances in feature films included Sweet November (1968), Targets (1968), If It's Tuesday, This Must Be Belgium (1969), The Out-of-Towners (1970), Birdy (1984), and others. Along with several of his contemporaries, Baron played himself in the opening scene of Woody Allen's Broadway Danny Rose (1984); he also narrated this film.