Arthur Hilary Armstrong, FBA (13 August 1909 – 16 October 1997) was an English educator and author. Armstrong is recognized as one of the foremost authorities on the philosophical teachings of Plotinus ca. 205–270 CE. His multi-volume translation of the philosopher's teachings is regarded as an essential tool of classical studies.
Hilary Armstrong was born in Hove, England. He was the son of W. A. (clergy) and E. Cripps Armstrong. He married Deborah Wilson in 1933. He has two sons and three daughters. He received a B.A. from Jesus College, Cambridge in 1932 and his M.A. in 1935. His hobbies and other interests included travel and gardening. He was made a fellow of the British Academy in 1970 and a fellow in the American Catholic Philosophical Association.
Armstrong began his teaching career in 1936 at University College, Swansea, Wales. His tenure at this university lasted until 1939. He then began teaching at the Royal University of Malta in Valletta as a professor of classics. In 1943, he became a classical sixth form master at Beaumont College, Old Windsor, Berkshire, England. Three years later, in 1946, he relocated to Cardiff University with the position of lecturer in Latin. From 1950-1972 he served as the Gladstone Professor of Greek at University of Liverpool in Liverpool, England, being appointed professor emeritus upon retirement 1972.
From 1970 to 1971, Armstrong was named a Killam Senior Fellow at Dalhousie University in Halifax, Nova Scotia, Canada. He also achieved a visiting professorship of classics and philosophy there beginning in 1972. He was also named a visiting professor at Manhattanville College in 1966. He was a founding Editor of Dionysius, together with J. A. Doull and R. D. Crouse.
In 1973, he won the Aquinas Medal from the American Catholic Philosophical Association.