Brennan, Martin (1900–56), revolutionary, doctor, politician, and film censor, was born 9 August 1900 in the family home at Rhue, Tubbercurry, Co. Sligo, sixth of thirteen children of Matthew Brennan (d. 1921), farmer and Fenian, and his wife Bridget (d. 1934), teacher, daughter of Thomas Brennan and Brigid Gallagher, farmers of Drimina, Co. Sligo. An exceptional student, he won scholarships to both St Nathy's College, Ballaghaderreen (1914–19), and UCG (1919–20, 1924–7). Having joined the Irish Volunteers in 1916 and campaigned against the introduction of conscription in the summer of 1918, he became captain of the UCG company of the IRA in 1920. Later the same year he suspended his study of medicine and returned to Sligo, where as a prominent member of the South Sligo Brigade active service unit, and later OC of the 4th Brigade column (3rd Western Division), he took part in the ambushes at Chaffpool (30 September 1920) and Culleen (1 June 1921), as well as the capture of the RIC barracks at Loughgeorge. Taking the anti-treaty side in the civil war, he was arrested in 1923 and sentenced to death, but after the intervention of Patrick Morrisroe, bishop of Achonry, he was reprieved. After a forty-two-day hunger-strike he was released in July 1924 and resumed his medical studies, graduating MB, B.Ch., BAO (1927). Between 1927 and 1932 Brennan held a series of short-term medical posts before being appointed district medical officer for the Aclare dispensary, Co. Sligo (1932–53). A Fianna Fáil TD for Sligo (1938–48), he only spoke seven times in the dáil and did not seek reelection in 1948. In January 1954 he succeeded Dr Richard Hayes (qv) (1882–1958) as the national film censor, and during his term of office (1954–6) banned 9 per cent of all films submitted, as compared to 5 per cent in 1946–53. He was the last film censor to respond to direct church intervention, when on 26 August 1954 the shot of the monstrance (bearing the blessed sacrament) was cut from Universal News no. 270.
A keen language revivalist, he assisted Séamus Ó Duilearga (qv) in the collection of over 500 folklore records in the west of Ireland and Tomás Ó Maille (qv) in his research on Irish dialects and philology. He included among his friends John Garvin (qv), Seán Moylan (qv), Tom Derrig (qv), and Ernie O'Malley (qv). Brennan died on 21 June 1956 in Dublin.
He married (4 February 1937) Sarah Patricia (d. 1993), daughter of John Foley, merchant, and Kate Foley (née Quinn) of Castle St., Sligo. They had three children and lived at Banada, Tourlestrane, Co. Sligo (1932–54), and at Rowan Park Avenue, Blackrock, Co. Dublin (1954–6). His nephew Matthew Brennan was Fianna Fáil TD for Sligo-Leitrim (1982–2002).