Fintan
Fionntán: either "white fire" or "white bull"
Fintan the Wise
According to The Book of Invasions, he is the only person (other than Noah and his crew) who survives the great deluge. He had come to Ireland with Cessair, granddaughter of Noah, to escape the coming flood; however, while everyone else drowned, Fintan was able to turn himself into a salmon (a symbol of wisdom) and spend the next forty days swiming in the sea. When the waters receded, he was the first man to set foot on Ireland again, and watched all the subsequent invasions in the form of a hawk or eagle.
Fintan the Historian
A possibly historical bard historian, whose history has become confused with the mythological Fintan. This Fintan's poetry and histories have been recorded in several Irish manuscripts, sometimes incorporated as part of the Book of Invasions.
St. Fintan of Clonenagh
b. 524, d. February 17, 594/597. A student of Saint Columbcille, he became a "green martyr" at the Slieve Bloom Mountains, near Maryborough, Queen's County. He then began the abbey at Clonenagh, where he attracted many followers, due to both his miracles and oratory skill, and is often called "Father of the Irish Monks."
St. Fintan (Munnu) of Taghmon
Feast day: October 21
d. 636. Son of St. Tulchan of Ulster, in 599 he founded the abbey of Taghmon (Teach Munnu--the House of Munnu), in Co. Wexford. He was the defender of the Irish method of dating Easter, and was vehemently opposed to the Roman church's way of dating Easter. This caused quite a schism for a while. However, the Roman church prevailed.
SOURCES FOR THE SAINTS:
http://www.newadvent.org/cathen/06078a.htm