He was the younger son of Richard II, Duke of Normandy, and his second wife, Papia of Envermeu.

[1] Mauger was brought up at the abbey of Fécamp as an eminent member of the ducal family, some of whom were later openly hostile to the accession of Duke William II.

Because of a perceived connection to his brother's rebellion, Mauger was deposed from his archbishopric at the council of Lisieux.

Stories relating to the end of Mauger's life in the Channel Islands were collected a century later by Wace (1100-1174), himself a native of Jersey.

The dethroned bishop is alleged to have abandoned himself to a pact with the devil and, having gone mad, drowned about 1055; his body was buried in a church at Cherbourg-Octeville.