Osraige or Osraighe, Osraí, anglicized as Ossory, was a medieval Irish kingdom comprising what is now County Kilkenny and western County Laois, corresponding to the Diocese of Ossory. The home of the Osraige people, it existed from around the first century until the Norman invasion of Ireland in the 12th century. It was ruled by the Dál Birn dynasty, whose medieval descendants assumed the surname Mac Giolla Phádraig.

Mac Giolla Phádraig is a native Irish dynastic surname which translates into English as "Son of the Devotee of (St.) Patrick". In the medieval period, the Mac Giolla Phádraigs were hereditary kings of Osraige; today, the anglicised version of the name is commonly "Fitzpatrick".