Infanta Mafalda of Portugal (Coimbra, 1149–1160) was a Portugueseinfanta, the second child and first daughter of Afonso I of Portugal (the first king of Portugal) and his wife Maud of Savoy. On 30 January 1159, when Mafalda was ten years old, her marriage was agreed with then Infante Alfonso of Aragon (future Alfonso II), who was seven. That would have made Mafalda the putative Queen consort of Aragon. However, the marriage did not happen, since the young infanta died in early 1160. This did not compromise the establishment of long-lived good relations between Portugal and Aragon, since Mafalda's younger brother Infante Sancho (future Sancho I of Portugal) would marry Dulce of Barcelona, Infanta of Aragon, sister of Alfonso II in 1175.