This name and family are Irish, and the heralds have gone very far back indeed to deduce their origin. They tell us, that Maoldabhreac, son of Fiobhrann, son of Finghin, descended from Heremon, second son of Milesius, was father of Ciorrovan or Kirrovan, from whom all the Irish Kirwans are descended. 

They appear to have settled in Galway, in the reign of Henry VI. about which time, the name first occurs in its modern form. The first mentioned being made of William Kirwan and his children. Some think they are much more ancient, supposing them to be the family of Kirwicke, already enumerated amongst the more early inhabitants of the town. This supposition is very probable, as the orthography of the name has undergone various changes, viz. O'Quirivan, Kyrvan, Kerovan, Kirevane, but it is now generally written Kirwan.

To this name and family, Ireland is indebted for two individuals, of the first order of genius, men whose splendid talents have raised their native country to a most elevated point in the scale of literature and science. By those the reader may easily anticipate, are meant the celebrated Dean Kirwan, and his distinguished relative and friend, the late Richard Kirwan, Esq. of Cregg. The former, acknowledged to have been the first Christian orator of his day, and the latter, one of the greatest philosophers of the age in which he lived.

The families of Blindwell, Castlehackett, Cregg, Gardenfield, Glan, Hillsbrook and Woodfield, in County Galway; and Dalgin, in County Mayo, are the principal of the name.