Duke William X of Aquitaine was a prominent nobleman in the 11th century, ruling from 1086 until his death in 1137. He was known for his significant influence in the region of Aquitaine in southwestern France. As a patron of the arts and a supporter of the Catholic Church, he played a crucial role in the cultural and religious life of his time. William X was also the father of Eleanor of Aquitaine, one of the most powerful and influential women in medieval Europe. His marriage alliances and political maneuvers helped shape the landscape of French nobility, contributing to the complex feudal system of the era.