Guillaume de Chanac (died December 30, 1383) was a French Benedictine who became a Cardinal.
He was abbot at Bèze Abbey, and then was abbot at Saint-Florent from 1354 to 1368. He was Bishop of Chartres and then Bishop of Mende, for brief periods up to 1371.
He supported the in Paris, named after his great-uncle of the same name.