Theresa (Portuguese: Teresa; Galician-Portuguese: Tareja or Tareixa; Latin: Tarasia) (c. 1080 – 11 November 1130) was Countess of Portugal, and for a time claimant to be its independent Queen.

She was recognised as Queen by Pope Paschal II in 1116, but was captured and forced to accept Portugal's vassalage to León in 1121, being allowed to keep her royal title.

[2] Her political alliance and amorous liaison with Galician nobleman Fernando Pérez de Traba led to her being ousted by her son, Afonso Henriques, who with the support of the Portuguese nobility and clergy, defeated her at the Battle of São Mamede in 1128.

Other historians, however, have showed that the pact could not have been made before 1103,[5][6] several years after the two counts had been granted their respective title, with Henry's appointment answering the need for military command in the southwest.

[7] At first, Theresa and Henry were vassals of her father, but Alfonso VI died in 1109, leaving his legitimate daughter, Queen Urraca of Léon as the heir to the throne.

[13] By 1128, the Archbishop of Braga and the main Portuguese feudal nobles had had enough of her persistent Galician alliance, which the first feared could favour the ecclesiastical pretensions of his new rival, the Galician Archbishop of Santiago de Compostela, Diego Gelmírez, who had just started to assert his pretensions to an alleged discovery of relics of Saint James in his town, as his way to gain power and riches over the other cathedrals in the Iberian Peninsula.