William I of Astarac

William I was count of Astarac in Gascony from 1022 or 1023, the eldest son of Count Arnold II and Talesa. When Arnold died, William took Astarac while his brother Bernard Pelagus received Pardiac. He made several grants of monasteries to Simorre Abbey and backed his brother Otto's restoration of Saramon.

His marriage to a kinswoman breached church rules and was validated only after penance. His last surviving charter is dated 1060, and his only son, Sancho I, succeeded him.