Giles Constable FBA (1 June 1929 – 17 January 2021) was an English historian of the Middle Ages.
Constable was mainly interested in the religion and culture of the 11th and 12th centuries, in particular the abbey of Cluny and its abbot Peter the Venerable.
He was the Henry Charles Lea-Professor of Medieval History at Harvard University from 1966 to 1977.
His most influential works, centered around the religious and cultural history of the twelfth century, illuminated the origins of monastic tithes, Peter the Venerable, the people and power of the Byzantine Empire, medieval religious and social thought, the reformation of the twelfth century, twelfth-century crusading, and the history of Cluny.
Constable was a Fellow of the Medieval Academy of America, the American Historical Association, the American Philosophical Society, the Académie des Inscriptions et Belles-Lettres, the Bavarian Academy of Sciences, the Bavarian Academy of Sciences, the British Academy, the Royal Historical Society, the Instituto Lombardo, the Accademia di Scienze e Lettere, and the Accademia Nazionale dei Lincei.