Mafalda of Portugal was a Portuguese princess and the queen consort of Castile. Born around 1195 to King Sancho I and Queen Dulce of Aragon, she entered a political marriage with the young Henry I of Castile in 1215. Because of their close kinship, the union was dissolved the following year, after which she returned to her native country. She eventually dedicated her life to religious service, becoming a nun at the Abbey of Arouca and later serving as its abbess.