William I, Count of Holland, was a nobleman who ruled from 1256 until his death in 1296. He was a member of the House of Avesnes and played a significant role in the political landscape of the Low Countries during the late 13th century. His reign was marked by efforts to strengthen the county's independence and expand its territory. William I was also known for his involvement in the conflicts between the House of Avesnes and the House of Dampierre. He worked to secure alliances and maintain stability in the region, contributing to the development of Holland as an important political entity in medieval Europe.