Hugh III de Montlhéry was a notable French nobleman from the Montlhéry family, active during the late 11th century. He was the son of Hugh II de Montlhéry and played a significant role in the feudal politics of the time. His lineage was tied to the powerful Capetian dynasty, which influenced the governance of France. Hugh III is best known for his marriage to Adelaide de Crépy, which strengthened his family's position. He held the title of Count of Montlhéry and was involved in various military campaigns, contributing to the territorial expansion and consolidation of noble power in the region.