Plunkett, Nicholas (c.1629–1718), historian, was born in north Co. Dublin, son of James Plunkett (d. 1739) and his wife Elizabeth Roper. Nothing is known of his early life. He succeeded to the family seat at Dunsoghly, Co. Dublin, in 1641, on the death of his grandfather. He saw military service in both Ireland and England in the late 1640s. Following further active service in Flanders in the 1650s, he returned to Ireland after the restoration of the monarchy in 1660. On his return he had difficulty in regaining his Dunsoghly estate, and instead took up residence at Harristown, Co. Dublin. Plunkett left Ireland in the 1680s, moving to London, where he had connections at the court of the queen dowager, Catherine of Braganza, through his mother's family, the Ropers, one of whom was a member of the queen's household. Plunkett spent two years in France following the Glorious Revolution, but on his return (1691) he took up residence in the queen dowager's residence, Somerset House. In 1692 he moved to the Somerset House apartments of Lady Fingall, a lady in waiting to Catherine of Braganza. His family connections, on both his father and mother's sides, had provided this entry to the upper echelons of London catholic society, as well as to one of the best-stocked libraries in the city, at Somerset House.
Plunkett is generally regarded as the author or compiler of the manuscript ‘An account of the war and rebellion in Ireland since 1641’, a work once thought to be by his namesake, the confederate catholic leader Sir Nicholas Plunkett (qv) (1602–80). According to Thomas Carte (qv), it was written by ‘a society of gentlemen’, and it seems likely that Plunkett and his collaborators worked at Somerset House, where the presence of an extensive library, featuring many of the works cited in the manuscript, made it an especially conducive venue for the production of such a work. Internal evidence, including references to Clarendon's History of the rebellion (1702) and the reign of King William (qv) and Queen Mary, suggest the work was ongoing through the 1690s and was not completed till the early eighteenth century. Only one-third of the manuscript, which is in the NLI, survives, having arrived there through descent from the Plunkett-Dunne family (MS 345). It was never published, but was used extensively by Thomas Carte in his Life of Ormonde (1736), while the same author was involved in an attempt to publish Plunkett's manuscript in 1741. Carte's use of Plunkett's work is not surprising, considering the general pro-Ormond tone of the work, which is strongly anti-clerical, and Plunkett's known association with and admiration for both dukes of Ormond.
Plunkett was formerly credited as the author of the Jacobite narrative, ‘A light to the blind’, but Patrick Kelly has authoritatively demonstrated that this attribution is erroneous, suggesting that it was actually the work of another Nicholas Plunkett, a brother of the 3rd earl of Fingall. Nicholas Plunkett of Dunsoghly does not seem to have returned to Ireland after the Williamite wars, while his non-participation on the Jacobite side ensured that he did not lose his estates. On his death (in London in 1718), he left money to fund an almshouse for catholic widows in Dublin.
He married twice; his first wife's name is unknown, but she bore him four children before her death sometime before his return to Ireland. He later married Elizabeth Fisher, with whom he had three further children. Neither marriage can be dated.