Professor Robert 'Roy' Foster is an Irish historian and academic.

After receiving his MA and PhD at Trinity College, where he was elected a scholar in History and Political Science in 1969, he began publishing as publishing as R. F. Foster. In 1989 he was elected Fellow of the British Academy and in 2010 he was elected an Honorary Member of the Royal Irish Academy. He is also an elected Fellow of the Royal Society of Literature and a Fellow of the Royal Historical Society. He has written early biographies of Charles Stewart Parnell and Lord Randolph Churchill, edited The Oxford History of Ireland (1989), and written Modern Ireland: 1600–1972 (1988) and several books of essays. Foster produced a two-part biography of W. B. Yeats, which was awarded the James Tait Black Memorial Prize, and collaborated with Fintan Cullen on a National Portrait Gallery exhibition, ‘Conquering England: the Irish in Victorian London’. He was Professor of Modern British History at Birkbeck, University of London and held visiting fellowships at Oxford and Princeton universities. He was the Carroll Professor of Irish History from 1991 until 2016 at Hertford College, Oxford. In 2015, he was awarded the British Academy Medal for his book Vivid Faces: The Revolutionary Generation in Ireland 1890–1923.