William de Valence (died 18 May 1296), born Guillaume de Lusignan, was a French nobleman and knight who became important in English politics due to his relationship to King Henry III of England.
He was heavily involved in the Second Barons' War, supporting the King and Prince Edward against the rebels led by Simon de Montfort.
He took the name de Valence ("of Valence") after his birthplace, Valence, near Lusignan.He was the fourth son of Isabella of AngoulĂŞme, widow of John, King of England, and her second husband, Hugh X of Lusignan, Count of La Marche, and was thus a half-brother to Henry III, and uncle to Edward I.
Author: Edward Wedlake Brayley Source: Edward Wedlake Brayley. The History and Antiquities of the Abbey Church of St. Peter, Westminster, vol. 2, 1823. — p.153. License: CC-PD-Mark PD Old