Manuel I (European Portuguese: [mɐnuˈɛɫ]; 31 May 1469 – 13 December 1521), known as the Fortunate (Portuguese: O Venturoso), was King of Portugal from 1495 to 1521. A member of the House of Aviz, Manuel was Duke of Beja and Viseu prior to succeeding his cousin, John II of Portugal, as monarch. Manuel ruled over a period of intensive expansion of the Portuguese Empire owing to the numerous Portuguese discoveries made during his reign. His sponsorship of Vasco da Gama led to the Portuguese discovery of the sea route to India in 1498, resulting in the creation of the Portuguese India Armadas, which guaranteed Portugal's monopoly on the spice trade. Manuel began the Portuguese colonization of the Americas and Portuguese India, and oversaw the establishment of a vast trade empire across Africa and Asia. He was also the first monarch to bear the title: By the Grace of God, King of Portugal and the Algarves, and the Sea from Both Sides of Africa, Lord of Guinea and the Conquest, Navigation and Commerce in Ethiopia, Arabia, Persia and India (Portuguese: Pela Graça de Deus, Rei de Portugal e dos Algarves, d'Aquém e d'Além-Mar em África, Senhor da Guiné e da Conquista, Navegação e Comércio da Etiópia, Arábia, Pérsia e Índia).

Manuel established the Casa da Índia, a royal institution that managed Portugal's monopolies and its imperial expansion. He financed numerous famed Portuguese navigators, including Pedro Álvares Cabral (who discovered Brazil), Afonso de Albuquerque (who established Portuguese hegemony in the Indian Ocean), among numerous others. The income from Portuguese trade monopolies and colonized lands made Manuel the wealthiest monarch in Europe, allowing him to be one of the great patrons of the Portuguese Renaissance, which produced many significant artistic and literary achievements. Manuel patronized numerous Portuguese intellectuals, including playwright Gil Vicente (called the father of Portuguese and Spanish theatre), physician Garcia de Orta (who pioneered tropical medicine), and mathematician Pedro Nunes (who developed the nonius and the rhumb line). The Manueline style, considered Portugal's national architecture, is named for the king.