Margaret Olwen MacMillan (born 23 December 1943) is a Canadian historian and professor at the University of Oxford. She is former provost of Trinity College, Toronto, and professor of history at the University of Toronto and previously at Ryerson University (now Toronto Metropolitan University). MacMillan is an expert on the history of international relations.
MacMillan was the 2018 Reith lecturer, giving five lectures across the globe on the theme of war under the title The Mark of Cain, the tour taking in London, York, Beirut, Belfast, and Ottawa.
