Duke of Medina Sidonia
Alfonso Pérez de Guzmán y de Guzmán-Zúñiga, 5th Duke of Medina Sidonia (d. 1549) was the son of Juan Alfonso Pérez de Guzmán, 3rd Duke of Medina Sidonia and became Duke of Medina Sidonia in 1512 when his half brother, Enrique Pérez de Guzmán, 4th Duke of Medina Sidonia died childless.