Saint Patrick (Latin: Patricius[2], Irish: Naomh Pádraig) was a Christian missionary and is regarded as the patron saint of Ireland along with Brigid of Kildare and Columba. Patrick was born in Britain. When he was about sixteen he was captured by Irish raiders and taken as a slave to Ireland, where he lived for six years before escaping and returning to his family. He entered the church, as his father and grandfather had before him, becoming a deacon and a bishop. He later returned to Ireland as a missionary, working in the north and west of the island, and by using Monasteries as the center for his missionary work had great success in the conversion of Ireland. By the seventh century he had become a patron saint of Ireland, and the foundations of Irish Christianity were attributed largely to him.

The available evidence does not allow the dates of Patrick's life to be fixed with certainty, but it appears that he was active as a missionary in Ireland during the second half of the fifth century. Two letters from him survive, along with later hagiographies from the seventh century onwards. Many of these works cannot be taken as authentic traditions. Uncritical acceptance of the Annals of Ulster (see below) would imply that he lived from 373 to 493, and ministered in northern Ireland from 433 onwards.