Dom Afonso I of Braganza was the first duke of Braganza and the eighth count of Barcelos. He founded the House of Braganza, the most powerful and wealthy dynasty in Portugal. His descendants became high-ranking nobles, imperial officials, and finally kings of Portugal and emperors of Brazil.

The title Duke of Braganza in the House of Braganza is one of the most important titles in the peerage of Portugal. Starting in 1640, when the House of Braganza acceded to the throne of Portugal, the male heir of the Portuguese Crown were known as Duke of Braganza, along with their style Prince of Beira or Prince of Brazil. The tradition of the heir to the throne being titled Duke of Braganza was revived by various pretenders after the establishment of the Portuguese Republic on 5 October 1910 to signify their claims to the throne.