The title character was voiced by Jason Alexander, most famous as Seinfeld's George Costanza. Other characters included his two-headed son Charles and Mambo (voices: Dana Hill & Elizabeth Daily), his obese teenage son Ajax (voice: Dweezil Zappa), and his business partner, a pig named Cornfed (voice: Gregg Berger). Nancy Travis voiced the characters of triplet sisters Bernice, Beverly, and Beatrice, Duckman's two sisters-in-law, and (supposedly) deceased wife, respectively.
One of the show's visual quirks was that Duckman's eyes were drawn on his glasses, making him look blind if he ever took them off.