Rex Fidelissimus in the context of "Kings of Portugal"

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.