| Afonso I | |
|---|---|
|   posthumous engraving; Carlos António Leoni | |
| Duke of Braganza | |
| Tenure | 30 December 1442 – 15 December 1461 | 
| Successor | Fernando I | 
| Born | 10 August 1377 Veiros, Estremoz, Alentejo, Kingdom of Portugal | 
| Died | 15 December 1461 (aged 84) Chaves, Trás-os-Montes, Kingdom of Portugal | 
| Spouse | Beatriz Pereira de Alvim Constance de Noronha | 
| Issue | Afonso, 1st Marquis of Valença Isabella, Lady of Reguengos de Monsaraz Fernando I, Duke of Braganza | 
| House | House of Braganza | 
| Father | João I of Portugal | 
| Mother | Inês Peres | 
| Religion | Roman Catholicism | 
Dom Afonso I of Braganza (Portuguese pronunciation: [ɐˈfõsu]; 10 August 1377 – 15 December 1461) was the first Duke of Braganza and the eighth Count of Barcelos. He would start a dynasty, the House of Braganza, that would end up being the most powerful and wealthy in all of Portugal. His descendents would go on to become high-ranking nobles, imperial officials, and even the Kings of Portugal and the Emperors of Brazil.
Historians believe he was born in Veiros, Estremoz, Alentejo, as a natural son of Portuguese King John I and Inês Peres. He married the heiress Beatriz Pereira de Alvim, daughter of Nuno Álvares Pereira, a general and the wealthiest man in the kingdom.
A traveled and cultivated man, Afonso was present in 1415 when the Portuguese conquered Ceuta. When his half-brother King Edward I of Portugal died in 1438, his son Afonso V (Afonso's nephew) was an infant and the choice for the regency was his sister-in-law, the Queen Mother Eleonor of Aragon.
This choice for the regency was not popular because Eleonor was Aragonese, so in a meeting of the Portuguese Cortes summoned by Afonso's half-brother John, Lord of Reguengos de Monsaraz, the regency was awarded to the Infante Peter, Duke of Coimbra, another half-brother of Afonso and an uncle of the young king. This choice pleased both the people and the fast-growing bourgeoisie.