Doag or Doak / Used for Davock in Ulster.

Dobbin / Doibin - Dod / Robert / English origins / They were in Co. Kilkenny - Western Leinster & Co. Waterford - North East Munster in 14th Century.

Dobbin / Doibin / English origins / They were in Co. Antrim - North East Ulster.

Dobbs / Robert / English origins / They were in Co. Antrim - North East Ulster in the 16th Century and were at Castledobbs.

Dobson / English origins / They were in Co. Leitrim - Northern Connacht.

Mac Dockery / Irish - Mheic Dhail Re Dochair / A Heremonian Dal Cuinn Ui Briuin Ai Sil Murray Clann Dail Military Sept - Family branch who were kinsmen to the O Connor Kings of Connacht & Ireland / They had their territory in Co. Roscommon - Eastern Connacht / It was corrupted to Mheic Giolla Deachair then because of this anglicized also as Harden & Hardy / deacair - hard / Ui Dochraigh now also used, which is incorrect / Kinsmen also to the Mac Dermots, Mac Donaghs etc. *87.Brion.

O Docherty / Irish - Ui Dochartagh - dochartach - stern / A Sept - Family branch who had their territory in Co. Donegal - North West Ulster and throughout Ulster.

O Docherty / Irish - Ui Dubhhatagh / A Sept - Family branch who had their territory in Co. Tipperary - Northern Munster.

Dodd / English origins / They came from Shropshire to Co. Sligo - North West Connacht in the late 16th Century and are now mostly in Co. Antrim & Co. Down - Eastern Ulster / Also used there as a synonym for Dowd, which see.

Doey or Dooey / Used as variants for Duffy, which see, in North East Ulster.

Dogget / English origins / They have been in Leinster since the 13th Century.

O Doheny or Downey / Irish - Ui Dubhchonna / An Ithian Corca Laoidhe Sept - Family branch who had their territory in Co. Cork - Southern Munster / Some migrated to the east of Munster where it was changed to Dawney. *35.Ith.

O Doherty / Irish - Ui Dochartaigh - dochartach - hurtful / A Heremonian Dal Cuin "Northern" Ui Niaill Ui Conaill Sept - Family branch whose territory was at Inishowen in Co. Donegal - North West Ulster / Also see Doorty & Dorrity. *88.Conall "Gulban."

O Dolain / Irish - Ui Dubhshlain - dubh - black / slan - challenge - defiance / A Heremonian Dal Cuinn Ui Maine Sept - Family branch who had their territory in Southern Co. Roscommon and Eastern Co. Galway - Southern Connacht. *80.Conn of the Hundred Battles.

O Dolain / Irish - Ui Doibhilin - dobhail - unlucky / Anglicized as Devlin, which see, in Co. Sligo - North West Connacht / They were also in Co. Cavan - Southern Ulster & Co. Mayo - Mid Western Connacht.

O Dolan / Originally O Doelan / Irish - Ui Doibhailen / A Heremonian Dal Cuinn Ui Maine Sept - Family branch who had their territory at Clonmacnowen in Co. Galway - Southern Connacht & Athlone in Co. Roscommon – Eastern Connacht / Now also in Co. Leitrim - Northern Connacht, Co. Cavan - Southern Ulster & Co. Fermanagh - South Western Ulster. *80. Conn of the Hundred Battles.

O Dolan / Irish - Ui Dubhhlain or Ui Dobhailen / Anglicized as Doolan & Dowling, which see.

Dolier / de Olier / French Huguenot origins / They were in Co. Dublin - Mid Eastern Leinster.

Dollard or Dullard / They were in Co. Dublin - Mid Eastern Leinster since the 13th Century.

O Dolly / Irish - Ui Dathlaoich - laoch - hero or champion / dath - swift / An important Sept - Family branch who had their territory in the Connemara in Co. Galway - Southern Connacht.

Dolohunty / Used as a variant for Delahunty, which see.

+On to  Dolphin - Dondon                                              *Irish Heritage