thumb|243px|Arms of William de Fortibus, Earl of Albemarle
William de Forz, 3rd Earl of Albemarle ( 1190 − 26 March 1242) was an English nobleman. He is described by William Stubbs as "a feudal adventurer of the worst type".
Family background
Forz was the son of William de Forz (died 1195), and Hawise, Countess of Aumale (died 11 March 1214), a daughter of William le Gros, 1st Earl of Albemarle. His father was a minor nobleman from the village of Fors in Poitou; the toponymic is variously rendered as Fors and Forz, or else Latinised to Fortibus.
Estate holdings
Soon after 1213, Albemarle was established by King John in the territories of the Earldom of Albemarle, and in 1215 the whole of his mother's estates were formally confirmed to him. In 1220 matters were brought to a crisis by his refusal to surrender the two royal castles of Rockingham and Sauvey of which he had been made constable in 1216. Henry III marched against them in person, the garrisons fled, and they fell without a blow. In the following year, however, Albemarle, in face of further efforts to reduce his power, rose in revolt.