William X, Count of Auvergne

William X (c. 1195–1247), count of Auvergne, was the son of Count Guy II and Péronnelle de Chambon. At eighteen he helped defend Tournoël, Auvergne's last free fortress, against Philip Augustus in 1213. He was taken in a failed sortie, and the castle's commander then surrendered.

He succeeded his father in 1222 as count of the remnant of Auvergne, and in 1229 or 1230 Louis IX restored several of his father's lordships to him. He married Adelaide of Brabant and died in 1247, leaving the county to his son Robert V.