Augustino de Cazalla (1510-1559), or Dr. Agustín Cazalla, was a Spanish clergyman, with humanist and Erasmist tendencies, who was prosecuted for founding a Protestant sect in Valladolid.The son of a royal accountant, Pedro de Cazalla, and Leonor de Vibero (or Vivero) - both were of 'converso' families - the nephew of Bishop Juan de Cazalla and the brother of María de Cazalla (of the group of illuminati in Guadalajara in 1525), he studied at the University of Valladolid with Bartolomé Carranza (who was also tried by the Spanish Inquisition) and at the University of Alcalá de Henares, where his uncle Juan was the former chaplain to Cardinal Cisneros and was also a renowned humanist and Erasmist. His classmate in Alcalá, Diego Laínez, was a founding member of the Society of Jesus.