The Norman Guitmund (died c. 1090–1095), Bishop of Aversa, was a Benedictine monk who was an opponent of the teachings of Berengar of Tours.
He attributes the perceived decay of the reserved sacrament, not as an accident of its essential substance (the orthodox view), but merely as a deception of our senses.
Shortly after Guitmund had published his treatise against Berengar, he obtained permission from his abbot, Odilo, to make a pilgrimage to Rome, where he lived for a time in a Roman monastery under the pseudonym of Christianus, which afforded him obscurity.
However, August Prévost, Ordericus' editor, states: "Guitmond n'a jamais été élevé au cardinalat.
Pope Urban II, formerly a monk at the Abbey of Cluny, appointed Guitmund as Bishop of Aversa at the Synod of Melfi in September 1089.