I would say Pope St. Leo (I) the Great. He was able to stop Attila the Hun from sacking the city of Rome just by talking to him. Granted, two angels with fiery swords standing behind him, but those were only visible to Attila. Also, Our Lady of the Rosary (also known as Our Lady of Victory). The Muslim (Ottoman Empire) expansion into Europe was halted at the Battle of Lepanto on October 7th,1571 (the day which would become her Feast Day).