Juan de la Cerda, 4th Duke of Medinaceli

Juan de la Cerda, 4th Duke of Medinaceli, (c. 1514 – 1575), Grandee of Spain, was a Spanish nobleman.

He was the son of Don Juan de la Cerda, 2nd Duke of Medinaceli, by second wife María de Silva. In 1552 Juan de la Cerda inherited the titles from his older half-brother Gastón de la Cerda y Portugal.

Both half brothers, the 3rd, Gaston, and the 4th Duke, Juan II, are widely reported in many places and articles as being born "out of marriage" from different women and being "legitimated" males by the Crown as legal successors to their father, the second duke Juan I, also, apparently, a legitimated bastard, however.

In 1557, King Philip II of Spain appointed him Viceroy of Sicily, a position he held until 1564. During that time he besieged with a fleet the North-African harbor of Tripoli, now in Libya, dealing with Dragut, a Turkish privateer and Ottoman admiral. The force, including ships from Spain, Genoa, Tuscany, the Knights of Malta and the Papal States, was however nearly destroyed in the Battle of Djerba.

In 1567 he was appointed Viceroy of Navarre supposedly staying there till 1572, but it seems that towards the end of 1570, he became head of the household of Queen Anna of Austria, position he held until his death in 1575.

In the spring of 1572 Philip II sent Medinaceli to the Netherlands as governor. According to Henry Kamen, Medinaceli reported to the king that “Excessive rigour, the misconduct of some officers and soldiers, and the Tenth Penny, are the cause of all the ills, and not heresy or rebellion.” [...] One of the governor’s officers reported that in the Netherlands “the name of the house of Alba” was held in abhorrence. Medinaceli lobbied the King for the removal of the Duke of Alba as military commander. Deciding that the views of Medinaceli and Alba were not compatible, Philip II removed both and replaced them with Requesens.