Fernando González Fernández (fl. 1380–1419), called Fernando de Illescas, was a Franciscan confessor, reformer and bibliophile, one of the most influential churchmen in Castile during the reigns of John I and Henry III, whom he served as a diplomat. A partisan of the Avignon Papacy at the height of the Western Schism, he attended the Council of Perpignan (1408) and the Council of Constance (1416), but played only a minor role in trying to end the schism.