Mac Costen - Mac Covera 

Mac Costen - Irish / Mheicc 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) 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. Ancestors: 78.Connla ancestor of the Ui Connla Septs, *60.Leary / Laoghaire the 68th King of Tara / Erinn (Ui Laoghaire), *59.Ugaine Mor -  the Great the 66th King of Tara / Erinn, *37.Eremon (Heremonians).

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

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

Costley. Used as a variant for Costello, which see.

Cott. See Coates.

Mac Cotter or Mac Cottyr or Mac Cottir - Irish /  Mheic Oitir / Oiteoir. Heberian Sept / Family branch, who had their territory at Ballymacotter in Co. Cork in Des Mhumhain / Desmond / Southern Munster. William Cotter, a son of Edmond Cotter had his Estate at Coppingstown Castle in Co. Cork that was confiscated after an Attainder was put on him by the English for being involved in the Irish Confederacy Uprising in 1641 AD 

Cottin / Choitin. They were in Co. Cork in Desmond / Southern Munster.

Cottingham -

O Cottle - Irish / Ua Coitil. Heremonian Dal Cuinn ""northern"" Ui Fiachrach Sept / Family branch, who had their territory in Co. Sligo in the north - west of the Connacht Province. Ancestors: 90. Fiachra the second Dal Cuinn King of Connacht (Ui Fiachrach), *89.Eochy Mugmedon the 124th King of Tara / Ireland.

Cotton. English toponymic origins 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 were in Downpatrick and the surrounding region in the south - east of the Ulster Province.

Mac Coughlan. See O Coghlan

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

Mac Coulahan or O Cuolahan Irish / Ua Uallachain. Heberian Sept / Family branch. Carol Mac Coulahan was the father of Donogh Keogh Mac Coulahan in 1602 AD, the father of Brian the father of Hugh the father of Hugh who died in 1667 AD whose son was Hugh who died in 1686 AD the father of Daniel who was a Lieutenant in James 11's army who was the father of Doctor John in 1761 AD who became a survivor and was the father of Hugh  the father of Daniel who married Francis Antisel of Arbour Hill in Co. Tipperary in Northern Munster and produced Hugh living in 1828 AD and Henry born in 1817 AD and still living in 1843 AD. 

O Coulahan. See O Cuolahan.

Coulter. See Colter.

O Coulton / Irish / Ua Comhailltain. Heremonian Dal Cuinn ""southern"" Ui Fiachrach Aidhne Sept / Family branch, Ancestors: *89.Eochy Mugmedon the 124th King of Tara / Ireland the father of  90.Fiachra the second Dal Cuinn King of Connacht and the direct male line ancestor of the Ui Fiachrach Septs who was the father of *91.Fearadach Dathi / Nathi the 127th King of Tara / Ireland the father of 92.Eochy / Echu who is the ancestor of the Ui Fiachrach Aidni Septs and the father of 93.Eoghan the father of 94.Conall the father of 95.Gabran the father of 96.Coffey / Cobhthach the father of 97.Colman the 11th King of Connacht the father of  98.Guarie Aidne the 14th King of Connacht the direct male line ancestor of the Cenel Guarie and the father of 99.Feargal a brother to 99.Murtough / Muirchertach the 15th King of Connacht, and 99.Artgal the ancestor of the O Shaughnessys and the father of 100.Fergal Aidne the 17th and last King of Connacht from the Ui Fiachrach Aidni Sept, 100.Toirbheartach the father of 101.Cathmogh the father of 102.Cumascach the father of 103.Ceadach the father of 104.Cleireach the direct male line ancestor of the O Clearys and the father of 105.Maol Fabhal who died in 887 AD the father of 106.Maol Ceardach aka Flann the father of 107.Comhailltan, the direct male line ancestor of the O Coultons / Ui Comhailltain, who died in 976 AD,

Coumey. See Comey.

O Counihan or O Cunighan or O Cunigan or O Cunningham or O Conyngham or O Cunnivane or O Conway  - Irish / Ua Cuineagain. Heremonian Dal Cuinn ""northern"" Ui Niaill Cenel nEogain Sept / Family branch. Ancestors: *89.Eochy / Eochaidh Mughmedhoin the 124th King of Ireland, *90.Niall - of the Nine Hostages the 126th King of Ireland and the direct male line ancestor of the Dal Cuinn Ui Niaill Septs, 91.Eogan the 1st King of Aileach and the direct male line ancestor of the Cenel nEogain Septs, 92.Murray / Muireadach the 2nd King of Aileach, whose brother was 92.Eochaidh Binne, 93.Tiernan / Tighearnan, 94.Daire , 95.Cunaghan - Warrior of the Battles the direct male line ancestor of the O Counihans / Ui Cunnigain, 96.Conall, 97.Awley / Amhailgadh, 98.Teague, / Tadhg, 99.Aodh, 100.Eoghan, 98.Mutaugh, 102.Eoghan, 103.Murtaugh, In 1680 AD Roger O Cunnivane was born who was the father of Timothy the father of Darby the father of Michael, the father of Thomas the father of Michael Cunningham of Ennis in Co. Clare in Northern Munster.  

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) English Earls in Co. Down in the south - east of the Ulster Province until he was replaced there vby 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.  They have been in Co. Dublin in the north - east of Southern Leinster since 1777 AD. Also Gaelicized as Mac Patrick.

O Courigan. See Corrigan.

O Cournane or O Courneen. See Curnane and Curneen.

Coursey. See de Courcy.

Mac Court or Mac Cuarta - Irish / Mheic Cuarta. Heremonian Dal Cuinn Colla Mac Uais Sept who had their territory in the Ulster Province. Ancestors: *86.Cairbre Liffeachair the 117th King of Tara / Ireland. 87.Eochy / Echu Doimhlen, 88.Colla Uais the 121st King of Tara / Ireland. 89.Roghan, 90.Erc, 91.Carthann, 92.Docherty / Dochartach, 93.Cormac, 94.Fergus, 95. Forannan, 96.Guarie, 97.Maolfogha, 98.Cathach, 99.Aodh. 100.Maolbreasal, 101.Maolcuairt (Mheic Cuarta)

Mac Court or Mac Courtney - Irish / Mac Cuarta / Mheic Cuairt. Heremonian 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: 101.Lugan, 100.Irgalach, 99.Eignigh, 98.Cormac, 97.Fergus, 96.Aed, 95.Cormac, 94.Cairpre Daim Argait, 93.Eochy / Echach, 92.Criffan / Crimthann Leith / Lethan, 91.Feicc, 90.Dega Duirn, 89.Rochatha / Rochadh, 88.Murray / Muireadach Colla Da Crioch / Focrith - of the Two Countries, 87.Eochy / Echu Doimhlen, *86.Cairbre Liffeachair the 117th King of Tara / Ireland.

O Courtayne. See Curtayne.

Mac Courtney. Heremonian 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.

Courtney / de Courtenai. Norman origins. Used to anglicize Cournane, which see. See also Curnane and it was also used for Mac Court, which see.

Cousins. See Cussen.

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

Mac Coveney - Irish / Mheic Coibheanaigh. 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 Lorc 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.