St Guillaume de Bourges, as birth name Guillaume de Corbeil, born in  1120 and died on January 10, 1209, is the archbishop of Bourges from 1199 to 1209. He is the St Guillaume of the calendar.

Son of Ferry V de Corbeil and his second wife1, he is a man "of pious character, devoted to study and meditation". Raised by Peter the Hermit, his uncle, he quickly turned to orders. He was the first canon of Soissons and then of Notre-Dame de Paris. Desiring peace and quiet, he became a monk at Grandmont Abbey. Dissensions having appeared in this order, he left it to become a monk at the Cistercian abbey of Pontigny where he stayed for a long time before becoming its prior. He then became abbot of Fontaine-Jean (in the commune of Saint-Maurice-sur-Aveyron), then abbot of Chaalis (diocese of Senlis) in 1187.

On November 23rd 1199, on the death of Henri de Sully, Archbishop of Bourges, he was designated to succeed him by Eudes, brother of Henri de Sully, Bishop of Paris and former cantor of the church of Bourges.

Considered a great preacher, firm on principle to such an extent that he drew the wrath of King Philip II of France at the time of his remarriage to Agnes of Merania, he fought at the request of Pope Innocent III against heretics, and in particular the Cathars. However, he fell ill while preparing a crusade against the Cathars.

He died on January 10, 1209. His body is placed in the centre of the still-unfinished cathedral, where a few days earlier he celebrated the epiphany, then in the crypt, where the representation of the Holy Sepulchre of Jesus Christ now stands, in a chapel built by Mahaut, Countess of Nevers, Lady of Donzy, his great-niece. She makes a donation, in a charter, to the church of Saint-Etienne for a candle to be burnt on her sepulchre, which charter, dated July 1223, describes her uncle as Saint William.

Following a series of miracles observed "through his intercession and before his tomb", Innocent III beatified him eight years after his death and Honorius III canonized him on May 17, 1218.

After the canonization, his body was exhumed and displayed on two columns behind the high altar until 1562. His relics were desecrated by the Calvinists in the 16th century and then during the Revolution, except for a rib that had been given to the College of Navarre in Paris by the canons of Bourges, and an arm bone entrusted to Chaalis.