Afonso VI (August 21, 1643 - September 12, 1675) was king of Portugal, the second king of the House of Braganza.
He succeeded his father in 1656 at the age of 16. His reign saw military victories over the Spanish at Ameixial (June 8 1663) and Montes Claros (June 17 1665), culminating in the final Spanish recognition of Portugal's independence on February 13, 1668. Colonial affairs saw the Dutch conquest of Jaffnapatam, Portugal's last colony in Sri Lanka (1658) and the cession of Bombay and Tangier to England (June 23 1661) as dowry for Afonso's sister, Catherine of Braganza who had married King Charles II of England. English mediation on 1661 saw Holland acknowledge Portuguese rule of Brazil in return for uncontested control of Sri Lanka. In 1667 Afonso was compelled by his estranged French wife and his brother, Pedro to abdicate the throne and was banished to the island of Terceira. These acts, which the mental instability of Afonso had rendered necessary, were sanctioned by the Cortes in 1668. He died at Sintra in 1675.