William IV Talvas (1179 – October 4, 1221) was William III, Count of Ponthieu and William IV (of the house of Belleme/Montgomery). He was Count of Ponthieu, ruler of a small province in northern France that fell under the suzerainty of the dukes of Normandy (later also kings of England) since at least the mid 11th century. He was son and heir of John I, Count of Ponthieu (d. 1191) by his third wife Beatrice de St Pol.