Born Albert Meister, he worked as a circus performer in the late 1920s before earning a Ph.D. in child psychology from Columbia University in 1941. In 1949, Lewis returned to acting, working in burlesque and vaudeville theaters before appearing on Broadway in the 1950s.
Lewis' first well-known television role was as Officer Leo Schnauser on "Car 54, Where Are You", although he is best remembered as Grampa on "The Munsters". Later, he opened an Italian restaurant called Grampa's in Greenwich Village, New York.
He ran as Green Party candidate for Governor of New York in 1998.