Ranulf de Briquessart or Ranulf the Viscount was an 11th century Norman magnate and viscount. Ranulf's family were connected to the House of Normandy by marriage, and, besides Odo, bishop of Bayeux, was the most powerful magnate in the Bessin region. He married Margaret, daughter of Richard Goz, viscount of the Avranchin and Emma de Conteville, whose son and successor Hugh d'Avranches became Earl of Chester in England. Ranulf is probably the "Ranulf the viscount" who witnessed a charter of William, Duke of Normandy, at Caen on 17 June 1066. Ranulf helped preside over a judgement in the curia of King William (as duke) in 1076 in which a disputed mill was awarded to the Abbey of Mont St. Michael. On 14 July 1080 he witnessed a charter to the Abbey of Lessay another in the same year addressed to Remigius de Fécamp bishop of Lincoln in favour of the Abbey of Préaux. and one more in the same period, to the Abbey of St Stephen of Caen. His name is attached to a memorandum in 1085, and on April 24, 1089 he witnessed a confirmation of Robert Curthose, Duke of Normandy and Count of Maine to St Mary of Bayeaux, where he appears below his son in the witness list. He probably died sometime after this. His son Ranulf le Meschin became ruler of Cumberland and later Earl of Chester. The Durham Liber Vitae, shows that his eldest son was one Richard, who died in youth, and that he had another son named William. He also had a daughter named Agnes, who later married Robert de Grandmesnil.