Thomas Bruce "T.B." Millar AO (18 October 1925 – 5 June 1994) was an Australian historian, political scientist and a major figure in the development of strategic studies in Australia.
Millar was born in Kalamunda, Western Australia. He was educated at Guildford Grammar School in Perth and the Universities of Western Australia, Melbourne and London. He was a graduate of the Royal Military College, Duntroon, and served in the Australian Army in 1943–1950.
After several years as a schoolteacher, he joined the staff of the Department of International Relations at the Australian National University in 1962. He was a professorial fellow in the department from 1968 onwards and head of the Strategic and Defence Studies Centre (SDSC) in 1966–1971 and 1982–1984. He was director of the Australian Institute of International Affairs, 1969-1976. In 1985 Millar was seconded to London University as professor of Australian studies and the foundation head of the Australian Studies Centre (then part of the Institute of Commonwealth Studies; now the Menzies Centre for Australian Studies at King's College London). Following his retirement in 1990, he remained in London until his death and held part-time positions at the London School of Economics and King's College London.