Afonso V of Portugal in the context of Pedro, Duke of Coimbra

This is a list of Portuguese monarchs who ruled from the establishment of the Kingdom of Portugal, in 1139, to the deposition of the Portuguese monarchy and creation of the Portuguese Republic with the 5 October 1910 revolution.

Through the nearly 800 years in which Portugal was a monarchy, the kings held various other titles and pretensions. Two kings of Portugal, Ferdinand I and Afonso V, claimed the crown of Castile and waged wars in order to enforce their respective claims. Ferdinand I managed to be recognized as King of Galiza in 1369, although his dominance of the region was short-lived. When the House of Habsburg came into power, the kings of Spain, Naples, and Sicily also became kings of Portugal. The House of Braganza brought numerous titles to the Portuguese Crown – some honorary, such as the attribution of the title of Rex Fidelissimus (His Most Faithful Majesty), and royal titles, such as King of Brazil and then de jure Emperor of Brazil.

The Treaty of Alcáçovas (also known as Treaty or Peace of Alcáçovas-Toledo) was signed on 4 September 1479 between the Catholic Monarchs of Castile and Aragon on one side and Afonso V and his son, Prince John of Portugal, on the other side.It put an end to the War of the Castilian Succession, which ended with a victory of the Castilians on land and a Portuguese victory on the sea. The four peace treaties signed at Alcáçovas reflected that outcome: Isabella was recognized as Queen of Castile while Portugal reached hegemony in the Atlantic Ocean.

The War of the Castilian Succession was the military conflict contested from 1475 to 1479 for the succession of the Crown of Castile fought between the supporters of Joanna 'la Beltraneja', reputed daughter of the late monarch Henry IV of Castile, and those of Henry's half-sister, Isabella, who was ultimately successful.

The war had a marked international character, as Isabella was married to Ferdinand, heir apparent to the Crown of Aragon, while Joanna was strategically married to King Afonso V of Portugal, her uncle, after the suggestion of her supporters. France intervened in support of Portugal, as they were rivals with Aragon for territory in Italy and Roussillon.

Count of Barcelos (in Portuguese Conde de Barcelos) is a title of nobility, the first to be granted in Portugal. It was created in 1298 by king Denis I and initially it was a non hereditary title, although most of the holders belonged to the Teles de Menezes family. It was only after the death of the 6th Count, when it was granted to Nuno Álvares Pereira, that the title became hereditary. The 8th Count of Barcelos was created Duke of Braganza in 1442, by his nephew king Afonso V, and his descendants rose to the Portuguese throne after the country regained its independence from Spain in 1640.

Initially, the seat of the Counts of Barcelos was the Palace of the Dukes of Barcelos, a large medieval structure that overlooks the Cávado river. After having been granted the Dukedom of Braganza, the family moved to a larger and more urbane palace in Guimarães, the Palace of the Dukes of Braganza.