William A. Horning (9 November 1904 — 2 March 1959) was the art director for the 1939 MGM film The Wizard of Oz. Horning was a graduate of the School of Architecture of the University of California. (Most of the twenty art directors at MGM had architectural training.) Horning's career in Hollywood extended from 1935 till his death. He received two posthumous Academy Award nominations in a single year, for North by Northwest and Ben Hur. He won the Oscar for Ben Hur. He had previously been nominated for Gigi (1958).