Crotty, William (1808–56), catholic priest and presbyterian minister, was born at Broadford, Co. Clare, son of Patrick Crotty and his wife Sarah (née Vaughan), and educated at the Irish college, Paris, being ordained priest there on 12 January 1832. He was appointed curate in the town of Killaloe to his uncle, Daniel Vaughan (1790?–1859), a future bishop of the diocese of Killaloe. Very soon, however, he was at Birr (known also as Parsonstown), King's Co. (Offaly), assisting his cousin Michael Crotty (qv), who, having been ordained priest in 1820, had been leading since 1826 a schism among local catholics, which by then was assuming a protestant tenor. Rivalry between the Crottys’ followers and the flock of the parish priest, Patrick Kennedy (another future catholic bishop of Killaloe), over use of a chapel produced much disorder, and in May 1834 the Crottys were arrested. Towards the end of 1835 they appealed to protestants for funds to build a chapel of their own; on 5 June 1836 mass was said there in English for the first time. When Michael Crotty went off to Belfast and Britain to collect money for its completion (August 1836), William Crotty took charge and led his cousin's remaining followers to a more advanced theological position. Consequently, in May 1839 William Crotty and 108 laymen successfully applied for connection with the Synod of Ulster – the main presbyterian body in Ireland. A prominent presbyterian minister, James Carlile (qv), having resigned his position as resident commissioner of national education, dedicated himself to missionary activity at Birr.
In December 1841 Crotty married and in 1842, probably unable to get on with Carlile, moved to Roundstone, Co. Galway, where his facility for speaking Irish made him an effective missionary for the presbyterian church (which, with little formality, had recognised his ordination). Later he contributed regularly to the church's Missionary Herald. When an American colporteur, Asenath Nicholson (qv), was there three years later she observed that ‘the catholics all spoke of him as a peace-maker wishing to do good to all and “given to hospitality”’ (Nicholson, 384). William Crotty died 25 July 1856 at Galway. His wife, Kate, daughter of Richard Dempsey of Mountmellick, bore him ten children, among them Albert Erasmus (1849–1936), who became a Church of Ireland minister in Co. Westmeath, Richard (1850–1924), who became a resident magistrate in Co. Clare, and Leslie (1852–1903), who became an opera singer.