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

Juan Alfonso Pérez de Guzmán, 3rd Duke of Medina Sidonia

Don Juan Alfonso Pérez de Guzmán y Afán de Ribera, 3rd Duke of Medina Sidonia inherited the title in 1492, aged 28. In 1502, as Gibraltar was transferred to the Crown, the Marquisate of Gibraltar disappeared....

 and became Duke of Medina Sidonia in 1512 when his half brother, Enrique Pérez de Guzmán, 4th Duke of Medina Sidonia

Enrique Pérez de Guzmán, 4th Duke of Medina Sidonia

Don Enrique Pérez de Guzmán y Fernández de Velasco, 4th Duke of Medina Sidonia was the son of Juan Alfonso Pérez de Guzmán, 3rd Duke of Medina Sidonia. He was Duke of Medina Sidonia from 1507. No issue by his wife María Téllez Girón....

 died childless.

Declared "impotent and stupid" ("mentecato", in 16th century Spanish language) by King Charles I of Spain in 1518, his wife Ana de Aragón, was the daughter of Alonso de Aragón

Alonso de Aragón

Alonso de Aragón or Alfonso de Aragón was Archbishop of Zaragoza, Archbishop of Valencia and Lieutenant General of Aragon. Born in Cervera, he was an illegitimate son of Ferdinand II of Aragon by a Catalan noblewoman called Aldonza Ruiz de Ivorra .- Ecclesiastical career :Aragón was more a...

, Archbishop of Zaragoza, the illegitimate son of Ferdinand II of Aragon

Ferdinand II of Aragon

Ferdinand the Catholic was King of Aragon , Sicily , Naples , Valencia, Sardinia, and Navarre, Count of Barcelona, jure uxoris King of Castile and then regent of that country also from 1508 to his death, in the name of...

. After the 5th duke's death, his widow married his brother Juan Alfonso, the 6th Duke.