Eustace I was a notable figure in the early medieval period, serving as the Count of Boulogne from around 1025 until his death in 1049. He was a member of the House of Boulogne and played a significant role in the political landscape of Normandy and England. Eustace was known for his military prowess and his involvement in various campaigns during his lifetime. He was the father of Eustace II, who succeeded him as Count of Boulogne. Eustace I's lineage contributed to the establishment of the Eustachian family, which would later play a prominent role in the history of England and France. His legacy is reflected in the continued influence of his descendants in medieval European politics.