Ruth Harris FBA (born 25 December 1958) is an American historian and academic. She has been Professor of Modern History at the University of Oxford since 2011 and a senior research fellow at All Souls College, Oxford, since 2016. Previously, she was a junior research fellow at St John's College, Oxford, from 1983 to 1987, an associate professor at Smith College from 1987 to 1990, and a fellow of New College, Oxford, between 1990 and 2016. She was awarded the Wolfson History Prize in 2010 for her book The Man on Devil's Island, a biography on Alfred Dreyfus.