Duke of Alba de Tormes (Spanish: Duque de Alba de Tormes), commonly known as Duke of Alba, is a title of Spanish nobility that is accompanied by the dignity of Grandee of Spain. In 1472, the title of Count of Alba de Tormes, inherited by García Álvarez de Toledo, was elevated to the title of Duke of Alba de Tormes by King Henry IV of Castile.
The dukedom of Alba de Tormes is one of the most significant noble titles of Spain and gives its name to the House of Alba. Over the centuries, three distinct families have succeeded to the title: the House of Álvarez de Toledo (extinct in 1755), the House of Silva (extinct in 1802), and the House of FitzJames, which descends from an illegitimate son of King James II of England.
Famous dukes include Don Fernando Alvarez de Toledo, 3rd Duke of Alba, governor of the Spanish Netherlands (references to "Alba" (Alva in Dutch), particularly in the context of Dutch history, are usually about him), and Doña María del Pilar de Silva, 13th Duchess of Alba, a muse of the painter Francisco Goya.
Various dukes have married into the families of Christopher Columbus and Cosimo de Medici, as well as the line of the Dukes of Berwick, making them distant relatives of the Earls Spencer and the Dukes of Marlborough.