St.William is best known as a missionary. Born at Saint-Germain, France, he served as a canon at the church of St. Genevieve, Paris, under the great Abbot Suger until about 1170, when he was sent to Denmark with the mission of spreading the Gospel. He became abbot there and, during his three decades among the Danes, he also reformed many other communities. He also founded the abbey of St. Thomas, in Zeeland. He died in Denmark.