O Dea - Irish / Ua Deaghaidh. A Heberian Dal gCais Cenel Cuallachta Sept / Family branch, who were the Chiefs of Dysert O Dea in the Parish of Dysert / Barony of Inchiquin in Co. Clare in the north - west of Thomond / Tuaisceart Mhumhain / Northern Munster. They were one of the main Dalcassian Septs in Co Clare who also anglicized their name as Godwin in Co. Mayo in the mid - west of the Connacht Province and also as Day and Daw, which see. They were also Chiefs in Co. Cork in Desmond / Des Mhumhain / Southern Munster and Kings in Co. Tipperary in the north - east of Ormond / Aur Mhumhain / Eastern Munster. Descended from *92.Aengus “Cinnathrach" / "Ceann Nathrach” the fifth son of *91.Cas the King of Thomond. Septs: The Cenel Fearmaic, the Cenel Baoi, the Cenel Cualochtaig / Cuallachta, and the O gRiobta Sept who was originally their main Family.  O Dee was sometimes also used incorrectly. Ancestors - *92.Angus "Cinnathrach," *91.Cas (Dal gCais) the King of Thomond.

O Deady - Irish / Ua Deadaigh. O Daoda is a variant that was also used that was anglicized as O Dady, which see. A Sept / Family branch, who had their territory in Co. Kerry and Co. Limerick in the west of the Munster Province.

O Deakin or O Deacon - Irish / Ua Deacain -

Deakin or Deacon. English origins. They were in Ireland in the 17th Century AD.

Mac Deale. They were in Co. Armagh in the south - east of the Ulster Province in 1664 AD.

Deane - Irish / Ua Deaghain. A Sept / Family branch, who had their territory in Co. Tipperary in the north - east of Ormond / Aur Mhumhain / Eastern Munster.

Mac Deane - Irish / Mheic an Deaganaigh - deaghan / dean. A Sept / Family branch - who had their territory in Co. Donegal in the north - west of the Ulster Province.

Deane / le Den. One of the "14 Foreign Tribes of Galway" who were in Co. Galway  in Southern Connacht. See also Dane in the north of Connacht.

Deane / le Denne. They were in the O Kennedy's Heberian kingdom of Ormond / North Eastern Munster in Co. Kilkenny / Ossory in the south - west of Southern Leinster and the surrounding territory in Co. Tipperary.

O Deany or O Deanie. Used as variants for O Denny, which see, in the Ulster Province and sometimes for O Deeney, which see. See also - Dealy.

Dease / Deise. They have been in Deece in Co. Westmeath in the south - west of Northern Leinster since the 13th Century AD.

O Deasy - Irish / Ua Deiseach / of the Decies. A Heremonian Ui Cobhthaigh Ui Felim Sept / Family branch, who had their territory in Co. Waterford in the south - east of the Munster Province who are now mainly to be found in Co. Cork in Desmond / Southern Munster. Ancestors - *79.Felim / Feidhlimidh "Reachtmar" - the Lawgiver the Heremonian Ui Cobhthaigh 108th  King of Tara / Ireland.

Mac Deasy - Irish / Mheic an Deisigh. A Sept / Family branch, who may have had their territory in Co. Sligo in the north - west of the Connacht Province?

O Dee - Irish / Ua Deaghaidh / Ua Diaghaidh. A Sept / Family branch, who are now in Desmond / Southern Munster. See - O Dea.

O Deegan - Irish / Ui Duibhgainn, dubh / black - ceann / head. An Irian Laeghis / Ui Laoighis Sept / Family branch, who were the Keepers of the Bell of St. Molua. from the O More / O Moore / Siol Mordha Sept who were also kinsmen to O Brophy / O Brofie / Ui Broithe, O Cashin / O Kissane / Ui Casain,  O Doran / O Dorrian / Ui Deoradhain, O Dowling / Ui Dunlaing, Mac Gahan / Mac Geehan / Mageehan / Mheic Gaethain, Mac Keady / Mac Keadie / Mac Keddy / Mac Keedie / Mac Keedy / Mackeady / Mheic Ceadach, O Harrigan / O Harraghan / O Harahan / Ui hArraghain, Ui Liathain, O Lalor / O Lawlor / Ui Leathlobhair, Mac Lee / Mac Lea / Ui Laoidhigh, O Swords / O Sord / O Sourdes / O Suard / Ui Suaird who had their territory at Cloncouse in Co. Laois in the mid - north - west of Southern Leinster. Ancestors - *Fachtna, *Milige, *Bran, *Eircc "hUbulchind," *Felim / Feidlimid mheic Finnchad, *78.Fiachach "Uanchind," *77.Daire, *76.Rossa, *75.Ogomain, *74.Fergus, *73.Muleist, *72.Fachtna, *71.Milige (Ui Baccan), *70.Intait, *69.Lugdach "Loichsi" / Laoiseach "Ceann Mor" the ancestor of the O More / Moore (Siol Morda) Sept in Co. Laois (named for him) in the north - west of Southern Leinster who were among the ”7 Septs of Laois, *68.Conall "Cernach" - of the Victories the leader of the Knights of the Red Branch of Ulster who is also the direct ancestor of the Mac Guinness, Mac Gowan and many other Irian Families in the Ulster Province and the Connacht Province. (He was a contemporary of Cuchulainn) *67.Aimhirgin "Larghiunach," *66.Cas, *65.Fachtna, *64.Cathbladh, *63.Cionga, *62.Rory / Ruaidri “Mor” - the Greater who died in 218 BC as the Irian 86th King of Tara / Erinn the direct ancestor of all of the Irian Families from the (Clann - na - Rory) Sept descended from *37.Ir (Irians).

 Deegan. A Sept / Family branch, who had their territory in Co. Clare in the north - west of Thomond / Tuaisceart Mhumhain / Northern Munster.

O Deehan - Irish / Ua Diochon. A Sept / Family branch, who had their territory in Co. Derry in the north - east of the Ulster Province. Sometimes changed to Dickson, Also see Deighan.

O Deeley - Irish / Ua Duibhghiolla - dubh / black - giolla / lad. A Sept / Family branch, who had their territory in Co. Galway in Southern Connacht. See also O Devilly, which was used as a synonym.

O Deenihan or O Dinaghan - Irish / Ua Duibhneachain. A Sept / Family branch, who had their territory in Co. Limerick in the mid - north - west of Thomond / Tuaisceart Mhumhain / Northern Munster who are now mainly in Co. Kerry in the south - west of Desmond / Southern Munster.

O Deeny or O Deeney or O Denny or O Deany or Peoples - Irish / Ua Duibhne - duibhne / disagreeable. A Heremonian Ui Cobhthaigh Dal Cuinn "Northern" Ui Niaill Cenel Conaill Siol Lugdach / Luighdech Sept / Family branch, who had their territory in the west of Co. Derry in the north - east of the Ulster Province and nearby in the east of Co. Donegal in the north - west of Ulster. Now mistranslated in English as Peoples from the Irish - similar sounding daoine. Kinsmen to the O Donnell / Ua Domhnaill, O Boyle / Ua Baoighill and O Doherty / Ui Dochartaigh. Clann Dalaigh / Ua Domhnaill, Clann Chindfaoladh / Ui Baoighill / Arda Midhair / Ui Dochartaigh. Ancestors - *91.Lugdach, *90.Setnai, *89.Fergus, *88.Conall "Gulban" the 1st King of Tir Conaill / Tyrconnell (Cenel Conaill), *87.Niall of the Nine Hostages the 126th King of Tara / Ireland (Ui Niall).

O Deere. See - Diver.

                                                                                +On to Deering - O Delaney