Gilbert of Assailly was the fifth Grand Master of the Knights Hospitaller, serving from 1162 or 1163 to 1170, when he was deposed. As Grand Master, he succeeded Auger de Balben. Nevertheless, most sources list him as the fifth, rather than fourth, Grand Master and this biography continues that tradition, with the exception being Delaville Le Roulx' work. He was succeeded by Gastone de Murols. Gilbert encouraged Amalric of Jerusalem in his unsuccessful invasion of Egypt, leaving the Order in debt and causing the reexamination of its military role.

Belvoir Castle, also called Coquet by the Crusaders, also Kochav HaYarden and Kawkab al-Hawa, is a Crusader castle in northern Israel, on a hill on the eastern edge of the Issachar Plateau, on the edge of Lower Galilee 20 kilometres (12 mi) south of the Sea of Galilee. Gilbert of Assailly, Grand Master of the Knights Hospitaller, began construction of the castle in 1168. The castle ruin is located in Belvoir National Park, officially Kochav HaYarden National Park. It is the best-preserved Crusader castle in Israel.