Count William I of Ponthieu was a nobleman in medieval France, known for his role in the region of Ponthieu. He was part of the House of Ponthieu, which played a significant role in the feudal system of the time. His reign is marked by efforts to strengthen his territory and maintain local power amidst the political complexities of the 11th century. William I was also known for his connections to other noble families, including the House of Normandy. His lineage and alliances helped shape the political landscape of northern France, influencing the relationships between various counts and dukes during his time.