He frequently portrayed characters who were verbally and/or physically abused in a slapstick way. Additional television credits include Twigs, All in the Family, Barney Miller, McMillan & Wife, Rhoda, Sanford and Son, The Mary Tyler Moore Show and several episodes of the Disney anthology television series. Additional film credits included roles in Catch-22 (1970), The Great Northfield Minnesota Raid (1972), A Reflection of Fear (1972), Emperor of the North Pole (1973), Papillon (1973), Killer Bees (1974), Bank Shot (1974), At Long Last Love (1975), The Night That Panicked America (1975), Peeper (1976) and High Velocity (1976).
Dunn's breakout role was as the judge (and Barbra Streisand's father) in the 1972 film What's Up, Doc?, in which he was noticed by Mel Brooks, who was in the process of forming a stock company of actors. Dunn went on to appear in Brooks films, Blazing Saddles (1974) as 'Rev. Johnson', Young Frankenstein (1974) as 'Mr. Hilltop', and as the 'Newsvendor' in Silent Movie (1976). He also appeared in several Walt Disney Productions, such as The World's Greatest Athlete (1973), Charley and the Angel (1973), Herbie Rides Again (1974) and Gus (1976).
Dunn collapsed on the set of Disney's The Shaggy D.A. (1976), during the filming of the roller rink sequence, and died soon after on April 11, 1976, from emphysema in Granada Hills, California. John Fiedler was brought in to complete the role as dog catcher. Though only 59 at his death, Dunn always looked much older, and was cast accordingly.
