William of Breteuil was a powerful Norman nobleman and Benedictine abbot who lived during the late 11th and early 12th centuries. As the lord of Breteuil, he inherited vast territories in central Normandy from his father, a companion of William the Conqueror. His life was marked by the political instability following the death of King William Rufus, during which he attempted to protect the English crown jewels. He eventually died at Bec Abbey in 1103 and is recognized as a saint in the Catholic tradition.