Mac Costen - Irish / Mheic Oistin (Descended from a son of Augustine) A Sept / Family branch, who had their territory in the east of Co. Cork in Desmond / Des Mhumhain /  Southern Munster, and nearby in Co. Waterford in the south - east of the Munster Province.

Mac Costigan - Irish / Mheic Oistoghin (Descended from a son of Roger) A Heremonian Ui Laoghaire Ui Connla Sept / Family branch. of the Fitz Patricks in Ossory, which see, who had their territory in Co. Laois in the mid - north - west of Southern Leinster. Ancestor - *78.Connla (Ui Connla), *60.Leary / Laoghaire the 68th King of Tara / Erinn, *59.Ugaine the Great the 66th King of Tara / Erinn, *37.Heremon (Heremonians).

Mac Costigan. A Heremonian Ui Laoghaire Ui Lughaidh Cu Corb Sept / Family branch. Ancestors - * 86.Cu "Corb," *60.Leary / Laoghaire the 68th King of Tara / Erinn, *59.Ugaine the Great the 66th King of Tara / Erinn, *37.Heremon (Heremonians).

Costley. English origins. They were in Co. Antrim in the north - east of the Ulster Province.

Mac Cotter - Irish / Mheic Oitir. A Sept / Family branch, who had their territory at Ballymacotter in Co. Cork in Desmond / Des Mhumhain / Southern Munster.

O Cottle - Irish / Ua Coitil. A Heremonian Ui Cobhthaigh Dal Cuinn "Northern" Ui Fiachrach Sept / Family branch, who had their territory in Co. Sligo in the north - west of the Connacht Province. Ancestor - *87. Fiachra the original 2nd King of Connacht (Ui Fiachrach), *86.Eochy "Mugmedon" the 124th King of Tara / Ireland.

Cotton. English toponymic origins. They have been in Co. Dublin and the south - east of Southern Leinster since the 17th Century AD.

Mac Coubre. Highland Scottish origins. Gaelic Irish / Mheic Cuithbreith (Descended from a son of Cuthbert) They were in Downpatrick and the surrounding region in the south - east of the Ulster Province.

Mac Coughlan - Irish / Mheic Cochlain - cochall / hood. A Heberian Dal gCais Sept / Family branch, who had their original territory in Co. Clare in the north - west of Thomond / Tuaiscert Mhumhain / Northern Munster. Their territory was later in Co. Offaly in the north - west of Southern Leinster, where they were a leading Family and the Chiefs of Delvin Mac Coughlan in the Banagher - Clonmacnoise region. As a Gaelic Family they continued to survive there until the 18th Century AD despite the continual English ethnic and religious oppression. Ancestor - *91.Cas (Dal gCais) the King of Thomond, *37.Heber "Fionn," (Heberians.)

O Coughlan or O Coghlan - Irish / Ua Cochlain. A Sept / Family branch, who had their territory at Barrymore in Co. Cork in Desmond / Des Mhumhain / Southern Munster. See also O Cawlin.

O Counihan - Irish / Ua Cuanachain. A Sept / Family branch, who had their territory in Co. Kerry in the south - west of Desmond / Des Mhumhain / Southern Munster. Some also used it as a synonym for Cunningham, which see. Coonan also used as a derivation.

County. See - Canty.

De Courcy or Decourcy / de Courci. French toponymic. Anglo Norman origins. Hibernized as de Cursa (Originally descended from Sir John de Courcy) they have been in Co. Dublin in the north - east of Southern Leinster since 1777 AD. English Earls in Co. Down in the south - east of the Ulster Province until replaced by de Lacy and were then English Barons in Kinsale and Clonakilty in the west of Co. Cork in Desmond / Southern Munster. John de Courcy himself was situated originally on the east - coast of Ulster. Also Gaelicized as Mac Patrick.

Mac Court or Mac Courtney - Irish / Mheic Cuarta / Mheic Cuairt. A Heremonian Ui Cobhthaigh Dal Cuinn Colla da Crioch Siol Daim Argait (Ui Cremthainn) Clann Lugainn Sept / Family branch, of the Maguires, who had their territory mainly in Co. Tyrone, and nearby in Co. Fermanagh in the south - west of the Ulster Province. Kinsmen also to Mac Alear / Mac Eleer / Mheic Gilla Uidhir, Mac Aleese / Mac Gileece / Mac Leece / Mac Illeese / Mac Leese / Mac Lice / Mac Lise etc / Mheic Giolla Iosa, Mac Anally / Mac Cowley / Mac Culloo / Mheic Con Uladh, Mac Auley / Mac Awley / Mac Gawley / Mheic Amhlaoibh. Mac Breen / Mheic Braoin, Mac Caffrey / Mac Godfrey / Mheic Gafraidh, Mac Cassidy / Mheic Asidha, Mac Cormack / Mheic Cormaic, Mac Corry / Mac Gorry / Mac Godfrey / Mac Gohery / Mac Goffrey / Mheic Gothraidh, O Darragh / O Darra / O Darrough / Oaks / Ui Dubhdhara, Mac Gee / Magee / Mheic Aodh, O Heany / O Heeny / O Hegney / O Higny / Bird / Ui hEgneach, Mac Lilly / Mac Calilly / Mac Lely / Mac Lillie / Mac Alilly / Mac Alyly / Mheic Ailghile, Mac Loughlin / Mac Lachlan / Mheic Lochlainn, Mac Manus / Mheic Maghnuis, Mac Morrow / Mac Murrow / Mheic Murchada (Clann Aodh). Ancestors - *98.Lugan, *97.Irgalach, *96.Eignigh, *95.Cormac, *94.Fergus, *93.Aed, *92.Cormac, *91.Cairpre "Daim Argait," *90.Eochy / Echach, *89.Criffan / Crimthann "Leith" / "Lethan," *88.Feicc, *87.Dega "Duirn," *86.Rochatha / Rochadh, *85.Murray / Muiredach "Colla da Crioch" / "Focrith"- of the Two Countries, *84.Eochy / Echu "Doimhlen," *83.Cairbre "Liffeachair" the 116th King of Tara / Ireland.

O Courtayne. See - Curtayne.

Mac Courtney. A Heremonian Ui Cobhthaigh Dal Cuinn Colla da Crioch Siol Daim Argait (Ui Cremthainn) Clann Lugainn Sept / Family branch, of the Maguires, who had their territory mainly in Co. Tyrone, and nearby in Co. Fermanagh in the south - west of the Ulster Province. Especially see - Mac Court.

Mac Courty. They were in Co. Leitrim in Northern Connacht.

Mac Coveney - Irish / Mheic Coibheanaigh. A Heremonian Ui Laoghaire Ui Lughaidh Cu Corb Sept / Family branch, who had their territory in the kingdom of Ossory in Co. Kilkenny in the south - west of Southern Leinster in the Crannagh Barony. Also now in Co. Cork in Desmond /  Southern Munster. Ancestors - *84.Cu "Corb," *60.Leary / Laoghaire the 68th King of Tara / Erinn, *59.Ugaine the Great the 66th King of Tara / Erinn.

Mac Covera. Used as a variant for Mac Coubrey, which see.

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