Luis Francisco de la Cerda y Aragón, 9th Duke of Medinaceli (2 August 1660, in El Puerto de Santa María – 26 January 1711, in Pamplona), 9th Duke of Medinaceli, was a Spanish noble and politician.

Eldest son of Valido Don Juan Francisco de la Cerda and Doña Catalina de Aragón Folc de Cardona y Córdoba, he inherited the titles of his father: Duke of Medinaceli, Duke of Alcalá de los Gazules, Marquis of Cogolludo, Marquis of Tarifa and Marquis of Alcalá de la Alameda, and from his mother Duke of Segorbe, Duke of Cardona, Duke of Lerma, Count of Empúries, Marquis of Denia, Marquis of Comares, Marquis of Pallars, and twice Grandee of Spain, making him one of the most important Spanish aristocrats of his time.

During the reign of King Charles II of Spain he served in Italy, being ambassador to the Holy See of Pope Innocent XII, and Viceroy and Captain General of Naples.

When Charles II died, he was appointed prime minister at the beginning of the War of Spanish Succession by the new King Philip V of Spain.

For this, he was incarcerated in the Alcázar of Segovia and later transferred to the castle of Pamplona, where he died the next year.