In early times when the population of Ireland was small and scattered, each individual was generally designated one (personal) name. Surnames or family names, as we understand them today were unknown, (Rev Patrick Woulfe – Irish Names and Surnames- 1993). The well established system of Irish clan names such as Ui Neill and Ui Briuin etc were formed from the names of distinguished ancestors but these names were used as a common designation for the entire clan. For example, the O’Gallagher’s, O’Boyles and other families traditionally descended from Conall Gulban, son of Niall of the Nine Hostages and they were located in Tirconnell (Donegal). For the individual the single personal name was the rule.

With the growth of population, commercial trade and travel, the single name system was no longer sufficient to enable a person to be identified and it became necessary to add a further distinction. Patronymic names came into use. Irish patronymic names were prefixed by Mac – taken from the name of the father and Ua (O) from the grandfather of the first person who bore the surname. Additional distinguishing epithets were added and these might include personal or physical characteristics, trade or profession, place of birth, age, size or any other peculiarities that would give individuality to the bearer. A modified version of this system still prevails in parts of Donegal where a surname commonly exists.

There is a divided and diverse opinion, as well as some agreement, on the history and origins of Irish surnames. Woulfe states that surnames in the modern sense are the growth of the 10th and three succeeding centuries and that during that period the patronymic, which before that was purely personal and changed with each generation, gradually became fixed and began to assume the hereditary and permanent character of a family name. MacLysaght adds that the principal cause of the distortion of Irish surnames was the introduction of the English language and the fact that documents relating to legal and official business were often prepared by clerks who were unfamiliar with Ireland. Distortion also gave rise to some surnames becoming known as a totally different surname, ie, Mac Giolla Bhrighde (MacGilbride) became Mucklebreed. He adds that changes in nomenclature also resulted from mistranslation, abbreviation and absorption of many surnames into similar sounding ones. Mistranslation was common due to the sound of part of the name, ie, Mac Giolla Eoin became Monday instead of MacAloon. Long names were abbreviated, ie Mac Giolla Iasachta became MacLysaght and then Lysaght. And finally the absorption of some surnames into those of similar sounding ones, ie Sullahan into Sullivan, Griffey to Griffen etc


Surnames common to County Donegal include:

Gallagher, Doherty, O’Donnell, Boyle, McLaughlin, Sweeney, Kelly, McDaid, Friel, McGinley, McFadden, Campbell, Gillespie, Breslin, Bonar, Brennan, McGowan, Ward, Galbraith, Alexander, Alcorn, Anderson, Brown, Campbell, Caulfield,
Colhoun, Craig, Dobbs, Dobson, Dodd, Elliott, Erskine, Fullerton, Hamilton, Harte, Hayes, Hunter, Irwin, Johnston, Lowry, McClintock, McCrea, McGill, McGuinness, Mclvor, McNight, McNutt, McLean, Magee, Morrison, Orr, Patton, Porter, Ramsey, Rankin, Robinson, Roulston, Scott, Sproule, Spear, Spence, Stewart, Taylor, Travers, Vaughan, Wilkinson, Wilson, Wray, Young and many others.