Walter III (French: Gautier), sometimes called Walter de Brisebarre or Walter Grenier (bef. 1180 – 24 June 1229), was the Constable of the Kingdom of Cyprus from 1206 and Lord of Caesarea in the Kingdom of Jerusalem from 1216. He was the eldest son of Juliana Grenier, Lady of Caesarea, and Guy de Brisebarre. Since he was witnessing royal charters by 1195, he must have been born no later than 1180. In the 1220s he was generally referred to as "the old lord of Caesarea", although probably only in his fifties.[1] He took part in two Crusades and in two civil wars on the side of the House of Ibelin.
As a young man, Walter was frequently in attendance at the royal court. He witnessed charters of Henry I in 1195–96, Amalric II in 1198, and the regent John of Ibelin in 1206. On an act of Amalric's he is term "lord of Caesarea", although his mother was still living, as was her second husband, Aymar de Lairon, who subscribed as "lord of Caesarea" to the same charter of John of Ibelin witnessed by Walter. In 1200 and 1206 he was a witness on charters of his mother and Aymar.[1]