Petronila of Aragon was a medieval queen born in 1136, the daughter of Ramiro II of Aragon. She became queen regnant of Aragon in 1137 when she married Berenguer IV, Count of Barcelona, uniting the crowns of Aragon and Catalonia. This marriage was significant in strengthening the political landscape of the region. Petronila's reign was marked by efforts to consolidate power and expand her kingdom. She played a crucial role in the establishment of the Crown of Aragon, which would later become a major Mediterranean power. Petronila's legacy is remembered for her contributions to the unification and governance of her territories.