Saint Brendan the Navigator
Saint Brendan was recognized as a saint due to his reputation for holiness and piety, as well as his missionary work in spreading Christianity. He is also known for undertaking a legendary sea voyage, which has been interpreted as a metaphor for his spiritual journey and dedication to spreading the word of God.
No, Irish is not the name of a saint.
Siobhan is a feminine Irish name. There is no evidence to suggest that there is, or ever was, a Saint named Siobhan.
Saint Brendan the Navigator died about the year 577 at Annaghdown (Enach Duin).
Saint Brendan was born around 484 AD in County Kerry, Ireland.
There is no saint named Niamh. She is a mythical Irish character.
Patrick brought Christianity to the Irish.
I imagine you are talking about (Brother) Saint Brendan. He was an Irish saint. His name means 'Prince' in Welsh. He is known for among other things, his Voyage across the Atlantic. http://en.wikipedia.org/wiki/Brendan - In Irish he is called 'Naomh Breandàn'
There is no record of a Saint Rebecca in Irish history or in the official list of Irish saints recognized by the Catholic Church. While there may be individuals named Rebecca who are venerated locally, there is no widely recognized Irish saint by that name.
Saint Patrick is the best known of the Irish saints.
Saint Brendan
Saint Cinnia was an Irish princess who was converted by Saint Patrick.