James O'Brien (1806-1882) was a nineteenth-century Irish barrister, politician and judge.
He was born in Granard, County Longford, a younger son of James O'Brien and Margaret Long. He went to school in Dublin, and entered the University of Dublin, where he graduated BA in 1829 with a gold medal in science. He entered Gray's Inn in 1831 and was called to the Irish Bar in 1831, Queen's Counsel in 1841.
He entered politics as a Liberal and was elected to the House of Commons as member for Limerick City in 1854, and was re-elected in 1857. He became Third Serjeant in 1848 and Second Serjeant in 1851. In 1858 he was appointed a judge of the Court of Queen's Bench (Ireland) and held office until his death. He died at his town house at St Stephen's Green; he also had a house in Dalkey.
He married Margaret Segrave in 1836 and they had five children: John, Anne, Emily, Clara, Mary and Margaret. Probably his most eminent relative was his nephew Peter O'Brien, 1st Baron O'Brien, Lord Chief Justice of Ireland, who was the son of his elder brother John O'Brien MP.