James O'Brien (1806-1882) was a nineteenth-century Irish barrister, politician and judge. He was born in Granard, County Longford, the fourth son of James O'Brien and Margaret Long, daughter of Peter Long of Waterford. His father died in February 1806, around the time James was born, and his mother remarried Cornelius O'Brien, MP for Clare, the County Clare politician and landowner. 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, becoming Queen's Counsel in 1841.