François Guillaume de Castelnau de Clermont-Lodève (1480–1541) was a French diplomat and Cardinal. He was the son of Pierre-Tristan, Seigneur de Clermont et de Clermont-Lodève and Vicomte de Nébouzan, and Catherine d'Amboise. His father was a member of the Order of Saint Michael. François' grandmother had been heiress of Dieudonné Guillaume de Clermont. He had an elder brother, Pierre de Castelnau, who was heir to the family estates. François was also the nephew of Cardinal Georges d'Amboise (1498-1510), who was largely responsible for François' swift rise to prominence in the Church. Cardinal d'Amboise had been Archbishop of Narbonne from 1491 to 1494.