O Daffy - Irish / Ua Deabhthaigh - deabhthach / quarrelsome. A Sept / Family branch, who had their territory in Co. Clare in the north - west of Thomond / Tuaisceart Mhumhain / Northern Munster.

Dagg. French English origins. - dague / dagger. They were in Co. Wexford and Co. Wicklow in the south - east of Southern Leinster in the 17th Century AD.

Mac Dagney - Irish / Mheic an Deaganaigh - deagan / dean. They were in the Ulster Province where it was usually changed to Dean, which see.

O Dahill - Irish / Ua Dathail. A Heremonian Ui Cobhthaigh Dal Cuinn Ui Briuin Siol Muiredaigh Sept / Family branch, who had their territory in Co. Roscommon in the east of the Connacht Province. They were also later in Co. Tipperary in the north - east of Ormond / North Eastern Munster. Ancestors - *87.Brion the original 1st King of Connacht (Ui Briuin), *86.Eochy "Mugmedon" the Nine Hostages the 124th King of Tara / Ireland.

O Dahony. Used as a variant for O Doheny, which see.

Mac Daid .Gaelic / Mheic Dhaibheid (Descended from a son of David) A Sept / Family branch, who had their territory in Co. Donegal in the north - west of the Ulster Province and nearby in Co. Derry in the north - east of Ulster. Also anglicized as Mac Davitt, Mac Devitt and Davison, which see.

Mac Dale - Irish / Mheic Dall / blind -

O Dallaghan or O Dalaghan - Irish / Ua Dalachain - dall / blind. A Clerical Sept / Family branch, who had their territory at Clonmacnoise in the Connacht Province, whose numbers were severely reduced during the Oliver Cromwell Invasion and ensuing massacres.

O Dallagher. Originally O Dologher, which see - Irish / Ua Dalachair. A Sept / Family branch, who had their territory in Co. Limerick in the mid - north - west of Thomond / Tuaiscert Mhumhain / Northern Munster.

O Dallan, A Heremonian Ui Cobhthaigh Dal Cuinn Colla da Crioch Ui Breasail Airthir / Orior Siol Fiachra Cassan Sept / Family branch. Especially see - O Dullahan.

Dallas. Originally Dalhouse (Dweller at the dale house.) Scottish origins. They were in Co. Derry in the north - east of the Ulster Province.

Dallon. Used as a variant for Delane, which see.

Dalton / de Dalatun. Originally de Alton. Anglo Norman origins. English Barons who were in Co. Meath and Co. Westmeath in the south of Northern Leinster who also had a sub - branch in Co. Clare and Co. Waterford in the Munster Province. They became "More Irish then the Irish."  See also Daton.

O Daly - Irish / Ua Dhalaigh - dalach - dail / Assembly. They were a Heremonian Ui Cobhthaigh Dal Cuinn Ui Maine Sept / Family branch,\ who had their territory in the Heremonian Ui Cobhthaigh Dal Cuinn "Southern" Ui Niaill Tuatha / Family region. They were present at the Assemblies as poets / Ollamhs in Co. Meath in the south - east of Northern Leinster. Their original territory was in Co. Westmeath in the south - west of Northern Leinster where they were Kings. They were later in Co. Sligo in the north - west of the Connacht Province and Co. Tyrone in Central Southern Ulster and they had a castle in Co. Galway in Southern Connacht. Although they originally had their territory in Co. Westmeath they also had other Septs in the west of Co. Cork in Desmond / Southern Munster, Co. Clare in the north - west of Thomond / Northern Munster and Co. Cavan in Southern Ulster. They were appointed English Barons in Co. Galway in Southern Connacht. Donagh "Mor" O Daly who died in 1244 AD was a poet and an Abbot who was from Boyle near Loch Key. Ancestors - *86.Maine "Mor" (Ui Maine), *85. Murray / Muiredach "Tireach" the 122nd King of Tara / Ireland, 80.Conn of the Hundred Battles the 110th King of Tara / Ireland (Dal Cuinn).

O Daly. A Sept / Family branch, who had their territory in Co. Kerry and Co. Cork in Desmond / Des Mhumhain / Southern Munster.

Dalzell. Pronounced Dee-ell. Scottish toponymic origins. They were in Co. Louth in the north - east of Northern Leinster and have been nearby in Co. Down in the the south - east of the Ulster Province since the 17th Century AD, after the Confiscation of the 3,500,000 acres of the Heremonian Ui Cobhthaigh Dal Cuinn "Northern" Ui Niaill territories there, and the Foreign non - Catholic Plantations there.

O Danaher or O Danagher - Irish / Ua Duineachair. Ua Danachair now used. A Sept / Family branch, who had their territory in Co. Tipperary in the north - east of Ormond / Aur Mhumhain / North Eastern Munster in the O Kennedy's Heberian kingdom of Lower Ormond, then later in Co. Limerick in the mid - north - west of Thomond / Northern Munster. They were also in Co. Cork in Desmond / Southern Munster.

O Danahy. Used as a variant for O Dennehy, which see.

                                                                                +On to Danceer - Mac Davett