Saint Fiachra (also called Fíachrach meic Colmáin; c. 500 – 25 July 558) was the Bishop of Armagh, Ireland from 548 to 558.
Saint Fiachra was a descendant of Muiredach Colla Fo Chrí, one of The Three Collas. His genealogy is "Fiachra m Colmain m Eoghain m Baodáin m Oilella m Suibhne m Maoileduin m Fionain m Oilella m Muireadhaig meith m Iomchadha m Colla da crioch”, which is also confirmed in the Naemsenchus Náemh nÉrenn as “Sil na cColla. 94. Fiacra mac Colmain do siol Colla-Da-Croich coir do reir eolach ni heccóir” His mother was an embroideress. Fiachra was born c. 500 AD in Enach Senmáil (The Marsh of the Ancient Prince).
On the death of Dubthach the Second, also called Duach II, the Bishop of Armagh, in 548, Saint Fiachra was appointed as the 10th successor to Saint Patrick. He reigned as Bishop for 10 years. In the old text Suidigud Tellaig Temra (The Settling of the Manor of Tara), the nobles of Ireland are attempting to partition Tara and they send for Fiachra as follows- "The nobles of Ireland were then summoned to the feast to the house of Tara by Diarmait son of Cerball. And they said that they would not partake of the feast of Tara until the settling of the manor of Tara was determined, how it was before their day and how it would be after them for all time, and they delivered that answer to Diarmait. And Diarmait replied that it was not right to ask him to partition the manor of Tara without taking counsel of Flann Febla son of Scannlan son of Fingen, that is, the head of Ireland and the successor of Patrick, or of Fiachra son of the embroideress. Messengers were accordingly dispatched to Fiachra son of Colman son of Eogan, and he was brought unto them to help them, for few were their learned men, and many were their unlearned, and numerous their contentions and their problems. Then Fiachra arrived, and they asked the same thing of him, namely to partition for them the manor of Tara. And he answered them that he would not give a decision on that matter until they should send for one wiser and older than himself. ‘Where is he?’ said they. ‘No hard matter that,’ said he, ‘even Cennfaelad son of Ailill son of Muiredach son of Eogan son of Niall. It is from his head,’ said he, ‘that the brain of forgetfulness was removed at the battle of Magh Rath, that is to say, he remembers all that he heard on the history of Ireland from that time down to the present day. It is right that he should come to decide for you."