Naish, John (1841–90), lawyer and lord chancellor of Ireland, was born at Ballycullen, Co. Limerick, second son of Carrol Naish, merchant, and Anna Margaret Naish (née O'Carroll); he came from a prosperous Roman Catholic family. Educated at Clongowes Wood College, Kildare, he entered TCD, where he graduated BA (1863) and received many awards and scholarships, including a double gold medal in mathematics and experimental science. Deciding on a legal career, he entered Lincoln's Inn and was called to the Irish bar (1865); he began practising on the Munster circuit. In 1871 he co-authored a work on common law procedure legislation that became a standard textbook on the subject. Too unassuming and nervous in court, Naish was unable to establish a reputation as a brilliant advocate. His vast knowledge of the law and its workings, however, compensated for his deficiencies as a speaker, and on 28 February 1880 he became QC, and law adviser to Dublin Castle. During the land league agitation he was obliged to find ways of prosecuting its leaders, and he skilfully used his considerable legal expertise for the benefit of the government. On 9 January 1883 the prime minister, Gladstone, appointed him solicitor general for Ireland, but he was defeated later that year by William O'Brien (qv) when he stood for election at Mallow to the house of commons.
Establishing a brilliant reputation as a legal expert, on 19 December 1883 he was appointed attorney general of Ireland, and made a privy councillor the following month. The highest legal office in Ireland was given to him on 21 May 1885 when Gladstone appointed him lord chancellor; he was only the second catholic to hold that position since the reformation. The collapse of the Liberal government soon after saw him replaced as lord chancellor on 1 July, and he was made a lord justice of appeal in August. He returned as lord chancellor in February 1886, but again the ministry did not last and by June he was once more a lord justice of appeal.
He died 17 August 1890 at Ems, Germany, and was buried there. He had been visiting the Continent to recover his health, and had been suffering from Bright's disease for some months. He married (1884) Maud Dease, of Turbotstown, Co. Westmeath; they had three children.