O'Connor, Dermot (ÓConchubhair, Diarmaid) (c.1690–c.1730), Irish scribe and translator of the history by Geoffrey Keating (qv), was the son of Tadhg Roe O'Connor of Limerick, a descendant of the O'Connors Kerry. The name of Dermot's mother is not known, nor do we know anything of Dermot's education, except that he could read and write Irish well. His scribal activity seems to have begun in Limerick in the years 1712–16, where he copied manuscripts for Tomás Bruinnebhíol and Dáibhí Ua Nihill, the latter a member of a fairly prosperous Limerick family. By the year 1719 O'Connor had moved to Dublin, where he met among others Seán Ó Neachtain (qv) and his son, Tadhg Ó Neachtain (qv). Seán and Tadhg were leaders of a circle of Irish scribes and scholars active in Dublin in the early eighteenth century. A poem written by Tadhg Ó Neachtain after 1726 lists all the members of their circle, including a slighting reference to Dermot O'Connor himself, who is called staraí ‘historian’. Seán Ó Neachtain composed two poems about O'Connor containing violent invective against him. While in Dublin O'Connor met another of the Ó Neachtain circle, Rev. Anthony Raymond (qv), vicar of Trim, fellow of TCD, and a close friend of Jonathan Swift (qv). Raymond had some knowledge of Irish, acquired in order to communicate with his parishioners in Co. Meath. Raymond also had a profound interest in Irish history and antiquities and was working on an English translation of Geoffrey Keating's Foras feasa ar Éirinn, a consecutive history of Ireland from the Creation until the Norman invasion. Recognising that his own knowledge of Irish was limited, Raymond employed O'Connor as an amanuensis to assist him in his enterprise.
O'Connor did not remain long in Raymond's employment, since in 1720 he went to London and immediately began circulating his own proposals for a translation of Keating's history, having, it seems, stolen the idea from Raymond. In London he visited Robert Harley, earl of Oxford, and also met Humphrey Wanley, the earl's librarian. While in London O'Connor obtained scribal work from Maurice O'Connor (qv), a practising barrister and the head of the family of O'Connor Faly, copying on vellum for him a version of Keating's history. This manuscript, now BL Add. MS 18745, was the text on which O'Connor based his own translation of Keating. O'Connor also visited Oxford, where he met the keeper of the Bodleian Library, Thomas Hearne, who in his diary refers to O'Connor on a number of occasions.
While in London O'Connor also worked as a heraldic painter and genealogist, providing pedigrees for Irish émigrés anxious to prove their nobiliary status. A certificate of arms drawn up by O'Connor for Mathew Quilty of Malaga survives, in which O'Connor styles himself antiquarius pro regno Hiberniae electus et juratus (‘Antiquary chosen and sworn for the kingdom of Ireland’). O'Connor was criticised for having adopted this unwarranted and spurious title. He was, none the less, well versed in heraldry and a competent artist. It is noteworthy that many of his manuscripts are unusual for the period in containing decorative initials. Furthermore, his translation of Keating contained twenty-eight plates of bilingual pedigrees and twelve plates (drawn by O'Connor) showing the coats of arms of the subscribers.
O'Connor's translation of Keating appeared in London in January 1722/3 under the title The general history of Ireland. A separate printing, aimed at the Irish market, appeared in Dublin in April 1723. O'Connor was vehemently attacked both during the preparation of the volume and after its publication. His two chief detractors were Anthony Raymond and Thomas O'Sullevane (sic). Raymond accused O'Connor, with some justification, of inaccuracy and invention. Raymond's main grievance, however, was that by bringing out his translation before Raymond's was ready, O'Connor had effectively prevented Raymond from ever publishing his own version. Thomas O'Sullevane, author of the dissertation prefixed to the Memoirs of the marquis of Clanricarde (1722), also accused O'Connor of poor scholarship; in particular he ridiculed O'Connor for suggesting that the Psalter of Cashel had been used as an additional source for the translation, when no such manuscript had existed for over 300 years. O'Sullevane also claimed that the real author of O'Connor's work was the controversial theist John Toland (qv), who had assisted Humphrey Wanley. Toland was almost certainly not the author of O'Connor's translation of Keating, but it is likely that he helped O'Connor in preparing his General history of Ireland for the press.
The dispute between O'Connor and his critics continued in newspapers and pamphlets for several years. In 1726 a new edition of O'Connor's book appeared in London, published by B. Creake, printer of the first edition. Two items by Anthony Raymond appeared in an appendix in this edition, a synchronism and a list of ancient place names together with their modern equivalents. Publishing matter by Raymond as part of O'Connor's work was presumably Creake's revenge on O'Connor, since Creake says in this work that O'Connor had absconded with £300 of subscription money collected for the original edition, leaving Creake to make good the loss out of his own pocket. About the year 1730 the London printer Daniel Wright published a collection of Scottish, Irish, and Welsh airs for the violin and oboe. Dermot O'Connor is mentioned on the title page as one of the three compilers, presumably having provided the Irish airs, about one-third of the collection. It seems, however, that O'Connor merely plagiarised a collection of Irish tunes published by William Neale (qv) in Dublin in 1724.
We know little of O'Connor's domestic affairs, though in his diary for 5 April 1726 Thomas Hearne says that O'Connor had been in prison, that ‘his nose is eat off with the pox, which he got by having two wives together, both, it seems, still living’, and he adds that O'Connor ‘is an horrid villain’. O'Connor himself disappears from view after the publication of Wright's musical collection and seems to have died at some time between 1729 and 1732. His translation, however, for all its faults, was very popular and between 1723 and 1865 at least twelve editions appeared.