Patrick is one of the best-known of the missionary saints. Born to a Christian family in Britain around the year 389, he was captured as a teenager by raiders, taken to Ireland, and forced to serve as a herdsman. After six years he escaped and found his way to a monastery community in France. Ordained a bishop in 432, he made his way back to Ireland, where he spent the rest of his long life spreading the Gospel and organizing Christian communities. He strongly defended the doctrine of the Holy Trinity in a time when it was not popular to do so. His literary legacy includes his autobiography, Confessio, and several prayers and hymns still used in the church today. Patrick died around the year 466.
For a longer bio, click here to go another Irishman's website, the Rev. Paul McCain's Cyberbrethren.
By the way, in case you were wondering, "Rath Dé ort!" is "God bless you!" in Gaelic.