William of Tudela (in Occitan, Guilhem de Tudela; in French, Guillaume de Tudèle; fl. 1199-1214) was the author of the first part of the Chanson de la Croisade Albigeoise or Song of the Albigensian Crusade, an epic poem in Occitan giving a contemporary account of the crusade against the Cathars. According to his own account in the first lines of his poem, William was born in Tudela in Navarre (Spain). He refers to himself as maestre and clerc, indicating that his studies entitled him to the title of Master and that he had taken minor orders. He specifically states that he studied geomancy.