bishop of Chartres who was regarded as the most learned canonist of his age.

Of noble birth, Ivo became prior of the canons regular of St. Quentin, Beauvais (c. 1078), and in 1090 Pope Urban II confirmed his election as bishop of Chartres. He was imprisoned in 1092 for opposing the plan of King Philip I of France to leave his wife, Bertha, and marry Countess Bertrade of Anjou. Ivo was released because of public pressure and the influence of Urban, who excommunicated Philip. At the Council of Beaugency (1104), Ivo recommended absolution for Philip, thus reconciling him with the Holy See. A moderate, Ivo served as mediator in the Investiture Conflict, a 12th-century dispute between the emperor and the papacy regarding the right to grant clerical office.

His importance as a canonist is displayed in his influential Decretum and his Panormia (17 and 8 books, respectively). His 288 letters reveal contemporary political, religious, and liturgical questions.