Dictionary of National Biography, 1885-1900/Grellan
GRELLAN, Saint (fl. 500), of Craebh-Grellain, in the south-east of the barony of Boyle, co. Roscommon, was the son of Cuillin, son of Cairbre Red-ear, king of Leinster. In the time of Lughaidh, son of Leogaire (483-508), great peals of thunder were heard, which St. Patrick interpreted as announcing Grellan's birth and future eminence as a saint. When of age to travel he abandoned his right of succession to the throne, and accompanied St. Patrick to Ath Cliath Duibhlinne (now Dublin). On this occasion Patrick is said to have composed a poem upon Grellan's future fame (given in Grellan's ‘Life’). They went from Dublin to Duach Galach, king of Connaught, whose wife was delivered of a dead child in the night. It was miraculously restored to life by the saints. As a reward for this Duach granted a tribute to be paid thenceforward by the descendants of the infant to Grellan, and bestowed on him the plain where the miracle was performed, then called Achadh Finnabrach, but afterwards Craebh-Grellain (the Branch of Grellan), from the branch given to him in token of possession by Duach and Patrick.
Grellan, travelling further, settled at Magh Senchineoil (the Plain of the Old Tribe), then the dwelling-place of Cian, king of the Fer Bolgs, who were the inhabitants of that territory. Cian waited on Grellan at Cill Cluana, now Kilclooney, north-west of Ballinasloe, in the barony of Clonmacnowen, co. Galway, where Grellan afterwards erected a church. The Fer Bolgs were attacked by a tribe from Clogher under Maine the Great, but Grellan intervened and made peace on condition that Maine should deliver ‘thrice nine’ nobles as hostages to Cian. Cian meditated a treacherous slaughter of the hostages, when, at Grellan's prayers, a quagmire opened and swallowed up him and his forces. Grellan then handed over the territory to Maine, and in return received the following tribute. He was to have a screpall (3d.) out of every townland, the first-born of every family was to be dedicated to him; he was also to have the firstlings of pig, sheep, and horse, and the race of Maine were never to be subdued as long as they held his crozier. This crozier was preserved for ages in the family of O'Cronelly, who were the ancient comharbas, or successors of the saint. It was in existence as late as 1836, when it was in the possession of John Cronelly, the senior representative of the saint's successors, but it is not known what has since become of it.
Grellan's day is 10 Nov., but the year of his death is not mentioned. Colgan says he was a disciple of St. Finnian of Clonard, and flourished in 590, but this is not consistent with the facts mentioned in the Irish life, for St. Patrick, with whom he is associated, died, according to the usual opinion, in 493, or, according to Mr. Whitley Stokes, in 463.
[Betha Grellain MS 23-0.41, Royal Irish Academy; Martyrology of Donegal, p. 303; O'Donovan's Tribes and Customs of Hy-many; Colgan's Acta Sanct. p. 337.]