Petronilla of Aragon was a medieval queen born around 1136, the daughter of Ramiro II of Aragon. She became the first queen regnant of Aragon when she ascended to the throne in 1137, following her father's abdication. Her marriage to Berenguer IV of Barcelona united the crowns of Aragon and Catalonia, strengthening the political landscape of the region. Petronilla's reign marked a significant period in the history of Aragon, as it laid the foundation for the future unification of the Crown of Aragon. She had several children, including Alfonso II of Aragon, who continued her legacy and expanded the kingdom's influence in the Iberian Peninsula.