His earliest television work includes appearances on the crime drama "Decoy" and "The Phil Silvers Show". From 1959 to 1963, he appeared in four episodes of "Naked City". Lewis' first well-known television role was as Officer Leo Schnauser on the sitcom "Car 54, Where Are You?" from 1961 to 1963, also starring Fred Gwynne (Lewis reprised the role in the 1994 movie of the same name). In the series, Lewis first played Al Spencer the Auto Body Man in two early first-season episodes, then landed the more familiar role of Officer Schnauser. He is best remembered as Grandpa on "The Munsters", which ran on CBS from 1964 to 1966.