The Spanish Empire was a colonial empire during the early modern period. Together with the Portuguese, it was one of the greatest empires in history. The Spaniards were the first to reach the European Age of Discovery on a global scale. They controlled large parts of the Americas, the Philippines, several islands of the Pacific, and areas of Western Europe and Africa.

The formation of the empire in 1469 was the union of Isabella I of Castile and Ferdinand II of Aragon. It was not a political unification. Under the Spanish Habsburgs (1516-1700), the structure of the empire was further defined. The Spanish Bourbon monarchs brought the empire under crown control and enlarged it through the papal grant of powers of patronage.

Philip II of Spain conquered Portugal after the War of the Portuguese Succession in 1581. Although Philip II gave Portugal some form of autonomy, all their territories came under the Spanish crown. The Spanish Empire in the Americas was formed after conquering native empires after Christopher Columbus' discovery of the Caribbean islands. In the 16th century, they conquered the Aztecs and Incas and converted the natives to Christianity. About 70 million of the 80 died during these conquests, partly due to disease epidemics.

Spain tried to give the empire a closed economic system. Reforms at the end of the 18th century no longer succeeded. Foreign merchants dominated the trade. The crown had to conspire with the merchant guild of Seville, which served as a trade intermediary.

Areas in America could largely be defended. At the beginning of the 19th century, American colonies began to fight for independence. By 1900 they lost many territories and possessions.