The title "Duke of Alcalá" is a noble title in Spain, historically associated with the city of Alcalá de Henares. It was first granted in the 15th century and has been held by various noble families over the years. The title signifies a high rank in the Spanish nobility and is often linked to significant landholdings and political influence. The most notable holder of the title was the Duke of Alcalá de los Gazules, who played a prominent role in Spanish history. The title is part of the broader system of Spanish nobility, which includes various ranks such as marquess, count, and baron.