This distinguished Irish surname is an Anglicized form of the Old Gaelic "O'Tuathail", descendant of Tuathal, an Old Celtic personal name composed of elements meaning "people, tribe", and "rule". Tuathal was the name borne by a 10th Century king of Leinster, of which province the O'Tuathails were one of the great septs, and it is from him that they claim descent. Glasthule, a village south-east of Dublin, written in Gaelic as "Glas-Tuathail", locates the sept, and translates as "Tuathal's" or "Toole's streamlet". The O'Tooles were remarkable for their unremitting resistance to Anglo-Norman attempts to conquer Ireland from the late 12th Century down to the end of the 17th Century, and in 1171 Laurence O'Toole, though then Archbishop of Dublin, took up arms against the Anglo-Norman invaders. In 1220, some thirty-eight years after his death, he was canonised and is patron saint of Dublin. A branch of this great Leinster family established itself in Connaught at an early date, settling in Counties Galway and Mayo where the name is widespread today. The O'Toole Coat of Arms is a red shield with a silver lion passant, the Crest being a boar passant proper. The first recorded spelling of the family name is shown to be that of Laurence O'Toole, first Irish Archbishop of Dublin, which was dated 1132 - 1182, in the "Medieval Ecclesiastical Records of Dublin", during the reign of Turlough Mor O'Connor, "High King of Ireland", 1119 - 1156. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.