Breslin, Cormac (1902–78), politician, was born 25 April 1902 in Ballindrait, Bunbeg, Co. Donegal, eldest of the seven children of John Breslin (d. 1919), hotelier and general merchant of Glenties, Co. Donegal, and his wife Mary (d. 1974), daughter of Daniel and Sorca Boyle, small farmers of Magheraclogher, Bunbeg, Co. Donegal. Educated at Knockastoler national school and St Eunan's College, Letterkenny (1915–19), he left school on his father's death to work in the family business. Having supported the anti-treaty forces during the civil war, he emigrated to New York, where he managed a shoe store. Returning to Ireland in 1931, he worked as a commercial traveller for McBirneys Ltd of Dublin (1931–6) before returning to Gweedore, where he established a furniture and drapery business in 1937.
Though reluctant to enter politics after the bitterness of the civil war, he became a member of Donegal county council (1937–67), serving as chairman of the county council and the vocational education committee. A Fianna Fáil TD for Donegal West (1937–61), Donegal South-West (1961–9), and Donegal–Leitrim (1969–77), he was leas cheann comhairle (1951–67) and ceann comhairle (November 1967–February 1973). As ceann comhairle he was ex-officio chairman of the Civil Service Commission and the Local Appointments Commission, chairman of the Irish Inter-parliamentary Union, of the dáil committee on privileges and procedures, and of Comhairle na Mire Gaile (Deeds of Bravery Council), and a member of the council of state and of the presidential commission. He also led parliamentary delegations to Japan, Brazil, Denmark, Peru, Hungary, France, and Yugoslavia.
Instrumental in the establishment of the Gweedore industrial estate, he was one of those involved in the establishment of the Gweedore Sea Angling Festival. He retired from public life in 1977 and died 23 January 1978 after a long illness.
He married in Dublin (November 1931) Antoinette Eugenie (d. 1989), daughter of Charles Wilman, market gardener, and Eugenie Wilman (née Dornberger) of Greenwich, Conneticut, whom he met in the USA; they had eight sons and two daughters. The family lived at Glenside, Bunbeg, Co. Donegal.