Saint Kerrill aka Caireall mac Curnain was a Christian missionary in what is now east County Galway, alive in the mid-to-late 5th century.
Caireall mac Curnain was a member of the Soghain people of Ireland, specifically those located in the kingdom of that name in what is now east County Galway. Dubhaltach Mac Fhirbhisigh identified them as part of a larger group called the Cruithin, and stated of them:
"Of the Cruithin of Ireland are the Dál Araidhi (Dál nAraidi), the seven Lóigisi of Leinster, the seven Soghain of Ireland, and every Conaille (see Conaille Muirtheimne) that is in Ireland."
The Soghain of Connacht were described by Seán Mór Ó Dubhagáin in his poem Triallam timcheall na Fodla where he states that:
"The six Sogain let us not shun/their kings are without oblivion/Good the host of plundering excursions/to whom the spear-armed Sogain is hereditary."
While the Book of Lecan lists their six branches as Cinel Rechta, Cinel Trena, Cinel Luchta, Cinel Fergna, Cinel Domaingen and Cinel Deigill.
Kerrill's genealogy is given as Caireall mac Curnain mac Treana mac Fionnchada mac Nair mac Earca mac Tiobraide mac Sodhain Salbhuidhe mac Fiacha Araidhe. His grandfather, Treana mac Fionnchada, was the eponym of the Cinel Trena, who were apparently located close to Knockma as envinced by the placename Tír Mhic Trena (the land of the sons of Trena).
Local tradition maintains that Saint Patrick did extensive missionary work among the Soghain. Kerrill was a disciple of Saint Benan of Kilbennan, Tuam. Benen was born in Tír Ailill, County Sligo, though his mother was from Kilbennan. Benen's grandfather, Lughaidh mac Netach, gave his fort at Kilbennan to St. Patrick to establish a fort over which he placed Benen, who set it up as a training school for evangelists.