Nihell, James (c.1650–1721), lawyer and MP, was the eldest among two sons and two daughters of Patrick and Anastace Nihell of Glasclowen, Co. Clare. The origins of the Nihell family are uncertain, one source suggesting viking ancestry while another claims they were descendants of the O'Neills of Ulster who settled in Co. Clare following defeat at the battle of Kinsale (1601). Patrick Nihell, an attorney, was granted permission to reside and work in the city of Limerick by the duke of Ormond (qv) in 1667, where he prospered under the patronage of the O'Brien family, earls of Thomond and Inchiquin. In 1673 he witnessed the will of Murrough O'Brien (qv), earl of Inchiquin, and he appears frequently as a witness to the numerous land transactions of the O'Brien family. In May 1681 Sir Joseph Williamson, former English secretary of state, and his wife Lady Catherine, widow of Henry O'Brien son of the 7th earl of Thomond, leased land at Dromoland to Patrick Nihell in trust for Lady Catherine's son, Donough O'Brien. The agreement obliged Patrick Nihell to serve at the manor courts of Bunratty and was signed by Stephen Rice (qv), future chief baron of the exchequer and a kinsman, by marriage, to the Nihell family.
By the 1670s Patrick Nihell was sufficiently prosperous to enable him to educate his eldest son at the inns of court, the first member of the family to acquire a formal legal education. According to his will, dated November 1703, Patrick Nihell possessed land in Co. Clare and a house at Ennis, as well as property in the liberties of Limerick. James Nihell entered Middle Temple in December 1675, where he remained at least until 1684. In 1683 he loaned £10,000 to the exchequer and also relieved Charles II of debts to his jeweller for gifts to envoys and mistresses alike, all transactions promising profitable rewards. Whether this was personal money, or whether Nihell was acting, more probably, on behalf of an unknown benefactor while at the inns of court, is not clear. In December 1683 he was one of seven Irishmen involved in riotous behaviour at the inn during the Christmas vacation. In May 1684 the offenders were expelled, charged with breaking down the doors of Middle Temple hall and – accompanied by many strangers with halberds – setting up gaming tables, a pastime strictly forbidden at the inns. The expulsion order was later rescinded following petitions from the accused.
James Nihell was appointed KC in April 1686, and in July, accompanied by Justin MacCarthy (qv), he visited Dublin Castle to appeal for greater flexibility in the admission of catholics to public office in line with the king's directions. By September 1686 Clarendon (qv), the Irish viceroy, admitted James Nihell and his father Patrick to membership of Limerick city council, absolving them from the oath of supremacy. In October, in response to additional pressure from Nihell, Clarendon nominated a further twelve catholics to the council.
James Nihell, in London during the autumn of 1687, wrote to Sir Joseph Williamson, to whom he had already been recommended by Sir Stephen Rice as counsel, offering to act as his counsel in Ireland. Apart from three cases recorded in the Irish chancery court between June and November 1688 where Nihell is listed as counsel, there is little evidence of his legal career. His particular interest appears to have been in the area of revenue and finance, possibly generated by his close association with Rice, baron of the exchequer court. He had many connections with men involved in the Irish revenue including Thomas Sheridan (qv), whose support he reputedly solicited against Tyrconnell's mismanagement of Irish affairs. He was also in correspondence with John Ellis (qv), secretary to the revenue commissioners, to whom he accounted himself indebted in February 1689. Nihell was appointed solicitor to the revenue commissioners on 27 April 1689, although when a new commission was issued (6 May) the clause containing Nihell's appointment was omitted. When parliament opened the following day, James Nihell took his seat in the commons as member for Harristown, Co. Kildare.
When parliament was prorogued in July 1689, James Nihell became involved in military affairs. Orders issued at a court martial at the King's Inns (August 1689) carried Nihell's signature, and as under-secretary to the earl of Melfort (qv) he published A journal of the most remarkable occurrences that happened between his majesties army and the forces under the command of Mareschal de Schomberg in Ireland from 12th August to 23rd October, 1689 (Dublin, 1689). After the battle of the Boyne (1 July 1690) he followed James II (qv) to France, where he remained as Melfort's secretary at least until 1693. His involvement in financial affairs continued at Saint-Germain, where he was in constant negotiation on matters of revenue between the exiled royal family and the French court. In 1709 he was financial controller to James III, the Old Pretender, and in 1714 was secretary to the dowager queen, working closely with her treasurer William Dickenson, a former Irish revenue commissioner appointed in 1689 at the same time as Nihell's appointment as solicitor. Nihell was frequently cited in the intrigues that surrounded the exiled court, particularly in 1703, when he was accused of being involved in a Jacobite plot to invade England. James Nihell died in Paris in 1721, aged 71 years.
He married (a. September 1686) Frances, daughter of Raphael Folliard, groom of the privy bedchamber to Charles II. They had four sons and four daughters, all born in France, though two daughters died early in childhood. Donogh MacCarthy (qv), 4th earl of Clancarty, was godfather to their eldest son, Denis, in April 1695; their second son, James, joined Dillon's Regiment, rising to the rank of lieutenant-colonel in 1745, following a distinguished military career. A third son, John (b. 1699), and his sister Henrietta were in Ireland in 1703. John inherited his grandfather's property in the liberties of Limerick, and remained in Ireland until his death in 1742.