Throughout the 1970s, Hackett appeared regularly in TV ads for Tuscan Dairy popsicles and yogurt. But his most famous television campaign was for Lay's potato chips ("Nobody can eat just one!") which ran from 1968 to 1971; Hackett had succeeded Bert Lahr as Lay's spokesman. He guest-starred in the "Space Rangers" episode, "To Be Or Not To Be", as has-been comedian Lenny Hacker, a parody of his stage persona. The character's name was Hackett's own real name. He also appeared on the television series “The Love Boat“ in 1979 (Season 3, Episode 4), playing the part of a cab driver, Mickey, who accepted an offer to join his jilted passenger (Arlene Golonka) on a three-day cruise. He also appeared in LA Law as a friend of Secretary Roxanne helping her by doing free TV infomercials.