Thomas Michael Tolliver Niles (born September 22, 1939, Lexington, Kentucky) is a diplomat who served as a career Foreign Service Officer and United States Ambassador to Canada (1985–89), the European Union (1989–91), and Greece (1993–97). He has since served as President and Vice Chairman of the United States Council for International Business and is a member of the American Academy of Diplomacy. He graduated from Harvard University and the University of Kentucky.