William the Clerk (French: Guillaume le Clerc) (fl.
c. 1200 – c. 1240) was an Old French poet known only from the self-attribution at the end of the Arthurian Roman de Fergus, a parody of the romances of Chrétien de Troyes, notably the Conte du Graal.
William may have been a Scoto-Norman, but the two manuscripts that preserve the Roman are from northeastern France, perhaps suggesting their provenance there.
Beate Schmolke-Hasselmann rejected this view and proposed that the Roman was commissioned by Dervorguilla, heiress of Galloway, and her husband, John I de Baliol, to promote the claim of their son, Hugh, to the Scottish throne, a claim derived from their ancestor Fergus Mor mac Eirc.
This dates the work later than their marriage, which took place around 1223, and prior to John's death in 1268, most likely between 1237 and 1241.