French author of the first and more poetic part of the medieval verse allegory the Roman de la rose, started by him c. 1225–30 but continued only some 40–50 years later by Jean de Meun.

Little is known of Guillaume de Lorris except that he was clearly an aristocrat and that he was born in the village of Lorris, just east of Orléans. Guillaume's section of the work—the first 4,058 lines—reveals him as a courtly poet of great perceptiveness who has mastered the revelation of character through allegorical symbols. It draws on the conventions of courtly love descended from the troubadours, although that code of behaviour appears to have been waning in popularity already in the 13th century.