Guillaume I de Craon

Guillaume I de Craon, called the Great (c. 1318–1388), second son of Amaury III de Craon by Béatrice de Roucy, founded the Châteaudun branch of his house. Around 1337 he traded his one-sixth share of Château-du-Loir to his cousin Pierre de Dreux for Domart-en-Ponthieu and Bernaville.

On 4 May 1341 he married Marguerite of Flanders-Termonde, Viscountess of Châteaudun, holding the viscounty through her. In 1345 he inherited La Ferté-Bernard from his brother-in-law Ingelger of Amboise, and served as a royal chamberlain.

In early 1361 he rode with Bertrand du Guesclin against Hugh Calveley at Juigné-sur-Sarthe, but midway through the battle he and eighty men-at-arms fled, leaving Du Guesclin to be captured. Of his eight children, sons Guillaume II, Pierre and Jean I continued the Châteaudun line.