Oia (rendered in Spanish as Oya) is a municipality in the province of Pontevedra, in the autonomous community of Galicia, in northwestern Spain. It lies within the comarca of Bajo Miño, in the far south of the province near the Portuguese border.
The municipality's most notable landmark is the Royal Monastery of Santa María de Oia, a former Cistercian monastery located in Oia. The monastery is the settlement's principal historic site and the feature most closely associated with the place.