Ó Cillín is the name of a family now rendered as Killeen (also Killian and Killion), found mainly in

County Roscommon County Roscommon () is a Counties of Ireland, county in Republic of Ireland, Ireland. It is part of the province of Connacht and the Northern and Western Region. It is the List of Irish counties by area, 11th largest Irish county by area and Li ...

County Mayo County Mayo (; ) is a Counties of Ireland, county in Republic of Ireland, Ireland. In the West Region, Ireland, West of Ireland, in the Provinces of Ireland, province of Connacht, it is named after the village of Mayo, County Mayo, Mayo, now ge ...

and

County Galway County Galway ( ; ) is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Northern and Western Region, taking up the south of the Provinces of Ireland, province of Connacht. The county population was 276,451 at the 20 ...

. It is derived from the saint's name Cillian.

Annalistic references

* ''966: Cormac ua Cillín, of the Ui Fhiachrach of Aidne, successor of

Ciarán Ciarán (Irish language, Irish spelling) or Ciaran (Scottish Gaelic spelling) is a traditionally male given name of Irish origin. It means "little dark one" or "little dark-haired one", produced by appending a diminutive suffix to ''ciar'' (" ...

and Comán and comarba of Tuaim Gréne — and by him was built the great church of Tuaim Gréne, and its bell-tower — a sage and an old man and a bishop, rested in Christ.'' * ''1026: Conall ua Cillín, successor of Crónán of Tuaim Gréine, rested.'' * ''1087: The battle of Conacla i.e. in

Corann Corann was an ancient Irish túath in northwest Connacht represented now by the present barony of Corran in County Sligo. The name is derived in legend from Corann, the harper of Dian Cecht of the Tuatha Dé Danann. Organisation Ballymote becam ...

, won by Ruaidrí ua Conchobuir and Cormac ua Cillín, chief vice-abbot of Síl Muiredaigh, with the staff of Ciarán in his hand before the battle when it was being fought between the

Connachta The Connachta are a group of medieval Irish dynasty, dynasties who claimed descent from the legendary High King of Ireland, High King Conn of the Hundred Battles, Conn Cétchathach (Conn of the Hundred Battles). The modern western Provinces of ...

and the

Conmaicne The Conmaicne (; ) were a people of early Ireland, perhaps related to the Laigin, who dispersed to various parts of Ireland. They settled in Connacht and Longford, giving their name to several Conmaicne territories. T. F. O'Rahilly's assertion ...

, and the Conmaicne were defeated, and there fell there Aed son of Art ua Ruairc, king of Conmaicne, and Muiredach ua Eolais and Sitric son of Cú Slébe ua Fergail and the son of Gafraidh ua Siridén and others. Ruaidrí ua Conchobuir was victor.'' * ''1106: Cormac ua Cillín, chief vice-abbot of Síl Muiredaigh and superior of the guest-house of Cluain moccu Nóis, rested in peace.'' * ''1186: Gillaberaigh O'Cillin, vice-abbot of Síl-Muiredhaigh, mortuus est..''

Sources

* https://web.archive.org/web/20120513074847/http://www.irishtimes.com/ancestor/surname/index.cfm?fuseaction=Go.&UserID= * http://www.ucc.ie/celt/published/T100016/ {{DEFAULTSORT:O Cillin Surnames Irish families Surnames of Irish origin Irish-language surnames