William I of Aquitaine, also known as William the Pious, was a prominent nobleman in the 9th century. He ruled the region of Aquitaine in southwestern France and was known for his strong leadership and support of the Church. His reign marked a period of relative stability and prosperity in the region. William was also a key figure in the development of monasticism, founding the famous Abbey of Cluny in 910. This abbey became a center for religious reform and significantly influenced the Benedictine order. His contributions to both governance and religion left a lasting legacy in medieval Europe.