Hugh Dudley Auchincloss Jr. (August 15, 1897 – November 20, 1976) was an American stockbroker and lawyer. He became the second husband of Nina S. Gore, mother of Gore Vidal, and also the second husband of Janet Lee Bouvier, the mother of First Lady Jacqueline Kennedy Onassis (wife of President John F. Kennedy) and Caroline Lee Bouvier.