Born in Tralee, County Kerry, in 484, Brendan was ordained a priest at age 26, whereupon he began to establish a series of monasteries.  He is most famous for the eggressio familiae Sancti Brendani, the Voyage of St. Brendan and his Companions, a seven-year journey in which Brendan sought the Isle of the Blessed, which he referred to as Tír na nÓg, taking the name from the realm of the faeries in Celtic mythology.  Upon his return, he continued to establish monasteries, the largest being at Clonfert, County Galway, as well as the Bishopric of Ardfert (now constituted as the Diocese of Kerry).  He died in 577 in Annaghdown, County Galway. 

Although there are those who scoff at Brendan's voyage as being purely legend, modern scholars have determined that there is a possibility of such a voyage having occurred.  One such enterprising individual even went so far as to recreate the Brendan Voyage, using the means and materials which would have been available in the early 6th Century, and successfully journeyed from Ireland to Newfoundland, reporting that he had seen many of the sights which Brendan was supposed to have seen.

It is, therefore, entirely plausible - and indeed, some might say probable - that St. Brendan was the first European to land on the North American continent, some 500 years before Lief Erickson, and roughly 1000 years before Christopher Columbus.  (We of course hold this to be definite, but we admit, we're slightly biased on the topic... )