William II (or III) (c. 987 – 1019), called the Pious, was the Count of Provence, succeeded his father, William I, on the latter's retirement to a monastery just before his death in late 993. He did not succeed in the margravial title, which went to his uncle Rotbold II. His mother was Adelaide of Anjou, who named William as son in a 1005 charter.
He participated in 1005 in the assembly, presided over by his mother, which regulated the conduct of the monastery of Saint-Victor. In 1018, the viscount of Fos revolted and refused to recognise Provençal suzerainty. He died besieging the vicecomital castle next year.
Lewis, Archibald R. The Development of Southern French and Catalan Society, 718–1050. University of Texas Press: Austin, 1965.