William III (915 – 3 April 963), called Towhead (French: Tête d'étoupe, Latin: Caput Stupe) from the color of his hair, is the "Count of the Duchy of Aquitaine" from 959 and Duke of Aquitaine from 962 to his death.

He is also the Count of Poitou (as William I) from 935 and Count of Auvergne from 950.

The primary sources for his reign are Ademar of Chabannes, Dudo of Saint-Quentin, and William of Jumièges.