John VI (Portuguese: João VI; 13 May 1767 – 10 March 1826), nicknamed "the Clement", was King of the United Kingdom of Portugal, Brazil and the Algarves from 1816 to 1822. Although the United Kingdom over which he ruled ceased to exist de facto beginning in 1822, he remained its monarch de jure between 1822 and 1825. After the recognition of Brazilian independence under the Treaty of Rio de Janeiro of 1825, he continued as King of Portugal and the Algarves until his death in 1826. Under the same treaty, he also became titular Emperor of Brazil for life, while his son, Emperor Pedro I, was both de facto and de jure the monarch of the newly-independent country.

Born in Lisbon in 1767, the son of Maria I and Peter III of Portugal, he was originally an infante (prince, but not heir to the throne) of Portugal. He only became heir to the throne when his older brother José, Prince of Brazil, died of smallpox in 1788 at the age of 27.

Before his accession to the Portuguese throne, John VI bore the titles Duke of Braganza and Duke of Beja, as well as Prince of Brazil. From 1799, he served as prince regent of Portugal (and later, from 1815, as prince regent of the United Kingdom of Portugal, Brazil and the Algarves), due to the mental illness of his mother, Queen Maria I. In 1816, he succeeded his mother as monarch of the Portuguese Empire, with no real change in his authority, since he already possessed absolute powers as regent.

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