Donegan

The most prominent dynasty were an Érainn people of the Múscraige and provided a King of Munster in the 10th century in the form of Flaithbertach mac Inmainén.

The O'Donegans were numerous at the end of the 16th century in the midlands and in North Connacht; and though by no means common, the name is at the present found in all provinces.

As Dinnegan it is found almost exclusively in County Longford especially Ballymahon where the family is a branch of Ó Donnagáin of Westmeath, where the name is usually anglicized as (O')Donegan and Dongan.

After holding the position of Archdeacon of Down, he held three successive bishoprics, Mann and the Isles (Sodor) where the Castletown branch of the family and their Manx variation of the surname, "Dunnigan", is common to this day.

Another distinguished member of the Castletown family was Thomas Dongan (1595–1663), younger brother to The Much Honored Sir John Dunnigan (1590–1669), Laird of Drumbreddan.

And therefore uncle to the TMH Sir John Dunnigan who fought under William III in the battle of the Boyne as an officer in the Ulster Protestant "skirmishers", with whom he had partaken in holding Derry the previous year.

Thomas was himself a lawyer who, after being reduced to dire poverty and disowned by his family by the aftermath of the Rising of 1641, became a Baron of the Exchequer at the Restoration.

Ó Donnagáin.
The coat of arms of the Dunnigan's of Ulster in given by TMH Lt Col John Dunnigan to genealogist William Fraser in 1717. The family crest is the Ermine in its animal form with an embedded heraldic ermine within. The shield contains four lions rampant with an ermine atop and below the red right hand of Ulster with the family motto "Virtus non vertitur" (Valour does not turn) beneath.
Thomas Dongan, 2nd Earl of Limerick .