Lope de Barrientos (1382–1469), sometimes called Obispo Barrientos ("Bishop Barrientos"), was a powerful clergyman and statesman of the Crown of Castile during the 15th century, although his prominence and the influence he wielded during his lifetime is not a subject of common study in Spanish history. From relatively humble beginnings in Medina del Campo, where he studied grammar, he took advantage of a secular custom of Castilian monarchs to selectively promote lower class court nobility to the service of Ferdinand I of Aragon—a privilege normally reserved for those of high birth.