Guillaume d'Estouteville (1403 – 1483) was a French ecclesiastic, He was bishop of Angers, then bishop of Digne, archbishop of Rouen, prior of Saint Martin des Champs, abbot of Mont St Michel, of St Ouen at Rouen, and of Montebourg. He was made a Cardinal in the consistory of December 18, 1439 by Pope Eugene IV, and later became Cardinal Bishop of Porto-Santa Rufina (1454), then Cardinal-Bishop of Ostia (1461) and Dean of the College of Cardinals (November 1472); he was a cardinal elector during the conclaves that elected Pope Nicholas V, Pope Paul II, and Pope Sixtus IV, but was absent from Rome during the sede vacante prior to the election of Pope Calixtus III. Camerlengo of the Holy Roman Church from 1477 until his death.