Ronald Ralph Schell (born December 23, 1931) is an American actor , stand-up comedian , and voice actor . He appeared on the May 28, 1959, episode of the TV quiz program You Bet Your Life , hosted by Groucho Marx . Schell demonstrated a comic barrage of beatnik jive talk.  As a stand-up comedian, he first developed his act at the hungry i nightclub in San Francisco, California. Schell is probably best known in his 1960s television role as Duke Slater in Gomer Pyle, U.S.M.C.