The title "Duke of Viseu" is a noble rank in the Portuguese nobility, historically associated with the region of Viseu in Portugal. It was first created in the 15th century and has been held by various members of the Portuguese royal family, including Prince Henry the Navigator, who played a significant role in the Age of Discoveries. The title has often been linked to significant political and military figures in Portuguese history. The Dukes of Viseu were influential in shaping the country's direction during the Renaissance and beyond, contributing to Portugal's expansion and exploration efforts across the globe.