Ivo of Chartres

Ivo of Chartres, Can.Reg., also Ives, Yves, or Yvo; ; 1040 – 23 December 1115), was a French canon regular and abbot who then served as the Bishop of Chartres from 1090 until his death. He was an important authority in Catholic canon law during the Investiture Crisis of that era. He is honored as a saint in the Catholic Church.

Three extensive canonical works, namely ''Tripartita'', ''Decretum'', and ''Panormia'', are attributed to him. He corresponded extensively. His liturgical feast is observed on 23 December. Provided by Wikipedia