Mac Giolla Phádraig dynasty
Mac Giolla Phádraig (Irish: [mˠək ɟɪl̪ˠə fˠaːd̪ˠɾˠəɟ]; Old Irish: Mac Gilla Pátraic) 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".
Source: Wikipedia — Mac Giolla Phádraig dynasty (CC BY-SA 4.0)