The Counts of Boulogne were noble rulers in the region of Boulogne-sur-Mer, located in northern France. This title emerged in the 10th century and was held by various noble families, notably the House of Boulogne. The counts played a significant role in the feudal system, managing lands and providing military support to the king. One of the most famous counts was Eustace II of Boulogne, who participated in the First Crusade in the late 11th century. The counts often engaged in conflicts with neighboring territories and were influential in the political landscape of medieval France and England.