In the reign of Ordoño I of Asturias (850–866), the kingdom began to be known as that of León. In 910, an independent Kingdom of León was founded when the king of Asturias divided his territory amongst his three sons.
Below follows a list of monarchs of León. It is, in part, a continuation of the list of Asturian monarchs.
Imperator totius Hispaniae is a Latin title meaning "Emperor of All Spain". In Spain in the Middle Ages, the title "emperor" (from Latin imperator) was used under a variety of circumstances from the ninth century onwards, but its usage peaked, as a formal and practical title, between 1086 and 1157. It was primarily used by the kings of León and Castile, but it also found currency in the Kingdom of Navarre and was employed by the counts of Castile and at least one duke of Galicia. It signalled at various points the king's equality with the rulers of the Byzantine Empire and Holy Roman Empire, his rule by conquest or military superiority, his rule over several ethnic or religious groups, and his claim to suzerainty over the other kings of the peninsula, both Christian and Muslim. The use of the imperial title received scant recognition outside of Spain and it had become largely forgotten by the thirteenth century.
The analogous feminine title, "empress" (Latin imperatrix), was less frequently used for the consorts of the emperors. Only one reigning queen, Urraca, had occasion to use it, but did so sparingly.
This is a list of Spanish heads of state, that is, monarchs and presidents that governed the country of Spain in the modern sense of the word. The forerunners of the Spanish throne were the following:
These lineages were eventually united by the marriage of the Catholic Monarchs, Ferdinand II of Aragon (king of the Crown of Aragon) and Isabella I of Castile (queen of the Crown of Castile). Although their kingdoms continued to be separate, with their personal union they ruled them together as one dominion. Spain was thereafter governed as a dynastic union by the House of Trastámara, the House of Habsburg, and the House of Bourbon until the Nueva Planta decrees merged Castile and Aragon into one kingdom.