O Diamond or O Dimon or O Dimond - Irish / Ua Diamain. An Erenagh Sept / Family branch, who had their territory in the east of Co. Derry in the north - east of the Ulster Province and are now also in Co. Donegal in the north west of Ulster and nearby in Northern Connacht. Definition of an Erenagh: By the 11th Century the Abbot in the churches was known as the Comharba / Co - Arb who was the heir of the Saintly founder / or, if this church was not the Saint’s main institution, the Airchinnech / Erenagh / head, who had become the lay Lord. His Family then held the office and the church property from generation to generation. Generally the Comharba or Airchinnech maintained a priest.

Dick / Richard. Scottish origins. They came into Ireland in the 17th Century AD into Co. Antrim and Co. Down in the east of the Ulster Province 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. Dix was also used as a synonym.

O Diffin. Used as a variant for O Duffin, which see, in Co. Armagh and Co. Tyrone in the south of the Ulster Province.

O Diffley or O Duffley. Used as variants for O Devilly, which see.

Mac Digany or Mac Digney - Irish / Mheic an Deaganaigh. See Mac Deane.

Digby. English origins. In 1689 AD they were granted the territory and Castle of the Irish Heremonian Ui Laoghaire Ui Lughaidh Cu Corb O Dempsey Chiefs, by the English.

O Diggin - Irish / Ua Duibhginn - dubh / black - ceann / head. A Sept / Family branch, who had their territory in Co. Kerry in the south - west of- Desmond / Des Mhumhain / Southern Munster. Usually pronounced O Duigan and O Deegan elsewhere.

O Dilgan - Irish / Ua Duibhleachain. A Sept / Family branch, who had their territory in Co. Clare in the north - west of Thomond / Tuaiscert Mhumhain / Northern Munster. Cognate with O Dullahan.

Dill. English origins. They were in Co. Donegal in the north - 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.

O Dillane - Irish / Ua Duilleain. A Sept / Family branch, who had their territory in Co. Limerick in the mid - north - west of Thomond / Tuaiscert Mhumhain / Northern Munster and in the north of Co. Kerry in the south - west of Desmond / Des Mhumhain / Southern Munster. Some changed to O Dillon, which see. Also used as a variant for O Delane, which see.

O Dilleen - Irish / Ua Duillin. Used as a variant for O Dillane, which see, in Co. Clare in the north - west of Thomond / Northern Munster and nearby in the south of Co. Galway in Southern Connacht.

Dillon. English Barons. They were in Co. Westmeath in the south - west of Northern Leinster, and nearby in Co. Galway in Southern Connacht at Loch Glinn where there is their original Family residence, which is now used as a Franciscan Convent for the Missionaries of Mary.

Dillon / Diolun. Norman Breton origins. (Descended from Sir Henry de Leon) who arrived into Ireland in 1185 AD. They took over control of Co. Longford and Co. Westmeath in the west of Northern Leinster where it was later known as "Dillon’s Country." They were 3 separate branches of English Earls who were in Co. Roscommon and Co. Mayo in the Connacht Province, and Co. Meath in the south - east of Northern Leinster and Co. Longford in the north - west of Northern Leinster. Also see - Dillane.

O Dinan or O Dynan - Irish / Ua Daghnain. A Sept / Family branch, who had their territory in Co. Tipperary in the north - east of Ormond / Aur Mhumhan / North Eastern Munster. They were the Chiefs of Uaithne whose territory was in the Barony of Owney Beg in Co. Limerick in the mid - north - west of Thomond / Tuaiscert Mhumhan / Northern Munster. They are now found in Co. Clare and Co. Cork in the Munster Province. Some of the O Dynans in Co. Cork also changed to O Dinneen.

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

                                                                                    +On to Dinerty - Dixon