Juan Alonso Pérez de Guzmán y de Guzmán-Zúñiga, 6th Duke of Medina Sidonia (24 March 1502 – 26 November 1558) was the son of Juan Alfonso Pérez de Guzmán, 3rd Duke of Medina Sidonia, half brother of Enrique Pérez de Guzmán, 4th Duke of Medina Sidonia, and the brother of Alfonso Pérez de Guzmán, 5th Duke of Medina Sidonia. Upon his brother's death in 1549, he became Duke of Medina Sidonia. In 1518 he married his brother's wife, (d. 1528), daughter of Alonso de Aragón, and had issue: * v * t * e