O Duignenan or O Deignan or O Dignam or O Duignan etc, - Irish / Ua Diubhgeannain. An Erenagh Sept / Family branch, who had their territory at Kilronan in Co. Roscommon in the east of the Connacht Province and nearby in Co. Leitrim in Northern Connacht. They were one of the most learned Families in Ireland. One of their Septs also went nearby into Co. Westmeath and Co. Longford in the west of Northern Leinster and Co. Cavan in Southern Ulster where they were known as O Deignan or O Dignam etc.

Duke - duc / leader. French origins. Or an abbreviation of Marmaduke. They have been in Ireland since the 16th Century AD, but some also came with the Oliver Cromwell Invasion and are found in the north - east of the Ulster Province and Northern Connacht.

Dukenfeild -

O Dulanty or O Dulhunty. A Heberian Cianacht Sept / Family branch. See especially - O Delahunty.

O Dullahan or O Dallaghan or O Dallahan or O Dallan or O Dolghan / Ui Dubhlachain. A Heremonian Ui Cobhthaigh Dal Cuinn Colla da Crioch Ui Breasail Airthir / Orior / Airthir Siol Fiachra Cassan Sept / Family branch who were kinsmen to the O Kealaghan / O Keelaghan / O Kealahan / Ui Ceileachain, Mac Cadden / Mac Cadigan / Mac Adam / Mac Adan / Mheic Acadhain, O Cashell / O Cassily / O Casley / O Cassell / O Cassely / O Cushley / Ui Caisile, O Kernaghan / O Kearnaghan / Ui Cearnachain, O Madigan / Ui Madadhain, O Trainor / O Trainer / O Trayner / Ui Threinfhir. They had their territory in Co. Louth in the the north - east of Northern Leinster and Co. Armagh in the south - east of the Ulster Province. Ancestors - *97.Buachalla, *96.Conor / Conchobar "Chorraig," *95.Mael "Duin," *94.Fingin, *93.Ronan, *92.Toole / Tuathal, *91.Ailella, *90.Conall, *89.Feicc, *88.Bressal, *87.Felim / Feidlimid, *86.Fiachra "Cassan," *85.Murray / Muiredach "Colla da Crioch" / Focrith" - of the Two Countries, *84.Eochy / Echu "Doimhlen," *83.Cairbre "Liffeachair" the 116th King of Tara / Ireland.

Dunbar. Scottish toponymic origins. They were in Co. Donegal and Co. Fermanagh in the west of the Ulster Province in the early 17th Century AD after the Confiscation of the 3,500,000 acres of the Heremonian Ui Cobhthaigh Dal Cuinn "Northern" Ui Niaill territories and the Foreign non - Catholic Plantations there. One of their branches were associated closely with James 11 and the Catholic Irish cause.

O Duncan. Used in Ireland as a synonym for O Donegan, which see. See also Dinkin.

Dundas. Scottish origins. They were in Co. Leitrim in Northern Connacht and nearby in Co. Fermanagh in the south - west of the Ulster Province.

Dunford or Dunfort. Used in Co. Waterford in south - east of the Munster Province as synonyms for Donarty, which see.

O Dunlea - Irish / Ua Duinnshleibhe. An Sept / Family branch, who had their territory in the west of Co. Cork in Desmond / Des Mhumhain / Southern Munster. O Dullea and O Delea were also used as variants. See also - Dunlevy.

Mac Dunlevy - Irish / Mheic Duinnshleibhe - Sliabh / mountain. A Dal Fiatach Sept / Family branch who were Kings of Ulidia / Ulaid, who had their territory in Co. Down in the south - east of the Ulster Province up until the 12th Century AD. They then migrated to Tir Conaill / Tyrconnell (The Land of 88.Connell) in Co. Donegal in the north - west of Ulster under the protection of the Heremonian Ui Cobhthaigh Dal Cuinn "Northern" Ui Niaill Cenel Conaill O Donnells following after those who went to the north of the Connacht Province in 1602 AD. A Sept also went over to Scotland, were they changed their name to Dunlop and Dunlief. Ancestors  - *109.Donn "Sliebe" the 56th King of Ulaid, **108.Eochy / Eochaidh the 52a King of Ulaid, *107.Niall the 52nd King of Ulaid, *106.Eochy / Eochaidh the 45th King of Ulaid, *105.Ardgal the 42nd King of Ulaid, *104.Matudan the 41st King of Ulaid, *103.Aed the 37th King of Ulaid, *90.Forgg mac Dallain.

Dunlop or Dunlief. See - Lappin and Mac Dunlevy.

O Dunn or O Dunne. Originally O Doyne the Lords of Iregan - Irish / Ui Doinn or Ui Duinn - Donn / brown swarthy hair. A Heremonian Ui Laoghaire Ui Lughaidh Cu Corb Sept / Family branch of the Hy / Ui Regan with their territory in Dooregan / Tuath Riagain anglicized as the Barony of Tinahinch / Tinne Hinch. It was in the north of the kingdom of Leix / Co. Laois in the mid - west  of Southern Leinster where they were Kings and Chiefs. They were cleared out of Cloneagh in Co. Laois twice by the English who introduced English Planters further into there to extend "The English Pale" surrounding Dublin in Co. Dublin in the north - east of Southern Leinster. They were also Kings and Chiefs nearby in Co. Meath in the south - east of Northern Leinster and Chiefs in Co. Kildare in Central Southern Leinster. Ancestors - *86.Cu "Corb," *85.Mogh "Corb," *84.Conor / Conchobar “Abhraiodhruaidh” the 99th King of Tara / Ireland.

O Dunn or O Dunne - Irish / Ua Doyne. A Sept / Family branch, who had their territory in the Heremonian Ui Cobhthaigh Dal Cuinn 3 Colla kingdom of Orghialla / Airghialla / Oriel in Southern Ulster.

O Dunnady. A Sept / Family branch, who had their territory in Co. Kerry in the south - west of Desmond / Des Mhumhain / Southern Munster.

O Dunnigan. A Heremonian Ui Cobhthaigh Dal Cuinn Colla da Crioch Cenel Rochada Fernmag (Fer Maighe) Farney Sept / Family branch, who had their territory in Co. Monaghan in Southern Ulster, Especially see - O Donegan.

                                                                                          +On to Dunning - Duvick