William d'Aubigny I (d. after 1148), was an itinerant justice under King Henry I of England. He was commonly known by the appellation Brito.
William was a son of Main d'Aubigny, Breton lord of Saint-Aubin-d'Aubigné (now in Ille-et-Vilaine department) and Adelaïde de Bohun, daughter of Humphrey with the Beard.[1] He fought at the Battle of Tinchebray (1106) and was high in Henry I's favour.[1] He was allowed to marry Cecily, the elder daughter of Roger Bigod, sheriff of Norfolk. Through her, he acquired a part of the honour of Belvoir in Leicestershire – his castle became the centre of the family estates – after his mother-in-law, who had been the heir of Robert de Todeni, lord of Belvoir, died about 1130.[1]
The couple had four or five sons and two daughters.[1] His heir was William, who married Maud Fitz Robert, daughter of Robert Fitz Richard. William d'Aubigny, a Magna Carta surety, was their son – his grandson.
His daughter Matildis married Gille Brigte, Earl of Strathearn.
After the death of King Henry I in 1135, William was and remained a loyal supporter of King Stephen, who presumably confirmed him in succession of Belvoir which passed to his son William.[2]