Constance of Portugal was a Portuguese princess born in 1430, the daughter of King Edward of Portugal and Leonor of Aragon. She became the Queen consort of Castile through her marriage to King Henry IV of Castile in 1440. This union was significant as it aimed to strengthen ties between Portugal and Castile during a time of political instability. Constance's life was marked by challenges, including her husband's struggles with legitimacy and political power. She had two children, but her marriage faced difficulties, leading to her eventual separation from Henry IV. Constance passed away in 1450, leaving a legacy intertwined with the history of the Iberian Peninsula.