Hugh Llewellyn Keenleyside, CC (7 July 1898 – September 27, 1992) was a Canadian university professor, diplomat, and civil servant. He was the Canadian ambassador to Mexico from 1944 to 1947, and the commissioner of the Northwest Territories from January 14, 1947 to September 15, 1950. From 1969 to 1977, he served as Chancellor and Chairman of the Board of Governors of Notre Dame University College. He published a two-volume memoir: Hammer the Golden Day and On the Bridge of Time.