genealogies of the families
Farren is a name closely associated with Co. Donegal where it is normally the anglicised form of Ó Faracháin. In O'Dugan's Topographical Poem and in the Book of Fenagh Ó Furadhran is described as Lord of Finross (now called the Rosses, in Co. Donegal) and the editors of both those works (John O'Donovan and William Hennessy) give Farren as the modern equivalent of that name, which however is distinct from Ó Faracháin. Ó Fearáin, a sept of the Cenél Eoghain, correctly anglicised Fearon in the counties of east Oriel (Armagh etc.), has tended to be changed to Farran in the case of families of the name living in Co. Donegal. O'Farran is listed as a principal name in the barony of Inishowen, Co. Donegal, in the 1659 "census", but the prefix 0 has since then been dropped and rarely resumed.
Farnan or Farnon is another Ulster surname some-what similar in sound. It was formerly Ó Forannáin in Irish (it is so spelt in the Annals of Loch Ce) and is now Ó Farannáin. This was an erenagh family of Ardstraw, Co. Tyrone.
The best known person of these names was Elizabeth Farren (1759-1829), a celebrated actress who at the age of 38 married the 12th Earl of Derby. She was born in Co. Cork, far from the country of the O'Farrens.
Source: More Irish Families by Edward MacLysaght MA, D Litt, MRIA - Irish Academic Press 1996