William Leonard Gammage AM, FASSA (born 1942) is an Australian academic historian, adjunct professor and senior research fellow at the Humanities Research Centre of the Australian National University (ANU).Gammage was born in Orange, New South Wales, went to Wagga Wagga High School and then to ANU. He was on the faculty of the University of Papua New Guinea and the University of Adelaide. He is a fellow of the Australian Academy of Social Sciences and deputy chair of the National Museum of Australia.