Guy de Montfort, Lord of Castres

Guy de Montfort (died 31 January 1228) was a French crusader and lord of Castres, younger son of Simon III de Montfort. He took part in the Third Crusade and joined the Fourth in 1202, but after Zara refused the Byzantine bargain and sailed to the Holy Land, where he married Helvis of Ibelin in 1204 and ruled Sidon as regent until 1210.

Back in France he fought in the Albigensian Crusade, notably at Muret in 1213. Wounded at Toulouse in 1218, he saw his brother Simon killed coming to his aid, and Guy himself was killed at the siege of Varilhes in 1228.