José Joaquín Álvarez de Toledo y Silva, 18th Duke of Medina Sidonia, GE (Madrid, Spain; 14 August 1826 – 15 February 1900) was a Spanish aristocrat and politician who served as Superior Chief of the Palace from 1885 until his death.
He was educated at the Theresian Military Academy, in Austro-Hungary, where his father was exiled for being a carlist sympathiser.
In 1847, Queen Isabella II lifted the seizure of the properties of the Medina Sidonias in Spain, and the family was able to return.
The young Pepe, by then Marquis of los Vélez, started his political career, taking a seat in 1852 at the Parliament of the Two Sicilies, as Prince of Paternò.
From 1885, he served as Superior Chief of Palace with King Alfonso XIII, and was part of the extraordinary embassy, headed by the Duke of Montpensier, sent to Russia in 1883 to represent Spain at the coronation of Tsar Alexander III.