David Andrew Day (born 24 June 1949) is an Australian historian, academic, and author.
The son of a weather forecaster with Australia's Bureau of Meteorology, Day grew up in Melbourne and Charleville, Queensland before commencing accounting studies in which he performed poorly owing to his political activity, which included protesting against Australia's involvement in the Vietnam War.
Day has been a Junior Research Fellow at Clare College in Cambridge, founding head of History and Political Science at Bond University, official historian of the Australian Customs Service, Keith Cameron Professor of Australian History at University College Dublin, and Professor of Australian Studies at the University of Tokyo.
His prize-winning history of Australia, Claiming a Continent, won the prestigious non-fiction prize in the 1998 South Australian Festival Awards for Literature.
John Curtin: A Life was shortlisted for the 2000 NSW Premier's Literary Awards' Douglas Stewart Prize for Non-Fiction.