William de Mandeville (died before 1130)[1] was an Anglo-Norman baron and Constable of the Tower of London.
William de Mandeville inherited the estates of his father Geoffrey de Mandeville, the Domesday tenant-in-chief, around 1100.[2] He was Constable of the Tower of London at that time,[3] and thus keeper of the first person known to be imprisoned there for political reasons, Ranulf Flambard. Flambard's escape in February 1101 would have significant consequences for William.[4]
It is not known if William was in some way complicit in the escape of Flambard, or was simply a careless keeper. Regardless, as a punishment, in 1103 Henry I confiscated the three richest of William's Essex estates, Sawbridgeworth, Saffron Walden, and Great Waltham, comprising about a third of his entire holdings, as well as the constableship giving them to Eudo Dapifer, William’s father-in-law.[5] [6] Little is known of William's activities after this.
William married Margaret, daughter of Eudo FitzHubert (Dapifer)[7] and Rohese de Clare. Widowed, Margaret married secondly Othuer fitz Earl (d. 1120), illegitimate son of Hugh d'Avranches, 1st Earl of Chester.[8] William and Margaret's son Geoffrey de Mandeville would recover the seized estates and the constableship during the reign of King Stephen.