The Countess of Hainaut was a noble title held by the female rulers or wives of the Counts of Hainaut, a historical region in present-day Belgium and northern France. The title was significant during the medieval period, as Hainaut was an important center of trade and politics. The countesses often played crucial roles in alliances through marriage and diplomacy. One notable Countess of Hainaut was Philippa of Hainaut, who became Queen of England by marrying Edward III in the 14th century. Her influence extended beyond Hainaut, as she was involved in various political matters and supported the arts and culture during her reign.