Ó Cléirigh (O'Clery), Lughaidh (c.1580–a.1630?), historian and poet, was born in Co. Donegal, the eldest of the five sons of Maccon Ó Cléirigh (d. 1595), who was ‘Ollav to O'Donnell in history, an erudite and ingenious man, professed in history and poetry’ (AFM, vi, 1961). His mother was from the south of Ireland. The O'Clerys were hereditary historians to the O'Donnell lords of Tír Conaill. Lughaidh was of the Sliocht Diarmada branch of the O'Clerys, descended from a man killed in 1522. It is recorded that he was educated at Ballymacegan in Ormond by Baothghalach Mac Aodhagáin along with Mícheál Ó Cléirigh (qv), one of the Four Masters. While Lughaidh is never mentioned in the annals, the death of his brother Duibhgheann Ó Cléirigh is recorded. Duibhgheann was killed in 1600 while accompanying one of Red Hugh O'Donnell's (qv) raids on Thomond; having been wounded accidentally by his own men, he died on the way home to Tír Conaill. His three other brothers were Giolla Bhrighde, Maccon Meirgeach, and Cuchoigcríche.
In 1603 Lughaidh Ó Cléirigh was a member of a commission set up to inquire into the boundaries of the lordship of Tír Conaill, which became Co. Donegal. In this record he is described as ‘a chronicler’ and was said to reside at a place called Doran (Irish patent rolls of James I, 47). In 1608 he was a signatory to a Latin indictment of the participants in the departure of the northern earls and the following year was one of nineteen jurors who sat at an inquisition at Lifford. Before the flight of the earls (September 1607), Ruaidhrí O'Donnell (qv), when made earl of Tyrconnell, mortgaged three-quarters of ‘Collumkillie's land’ in the parish of Drumhome to Ó Cléirigh for £40. After O'Donnell had left, Ó Cléirigh paid King James £4, two sheep, and a pair of gloves each year for this land. In 1610 he had to exchange his estate for a grant of 64 acres in the barony of Kilmacrennan as part of the native settlement in the plantation of Ulster. This demonstrates his continued high standing with the new order.
From 1616 to 1624 Ó Cléirigh was involved in the poetic contest known as Iomarbhágh na bhfileadh – the contention of the bards – a lively competition carried out in verse between poets from the north and south of Ireland over which part of the country could lay claim to being the most noble. It was begun by Tadhg Mac Dáire Mac Bhruaideadha (qv), a leading chief poet of Thomond, and Ó Cléirigh contributed four poems, which begin: ‘A Thaidhg ná tathaoir Torna’ (O Tadhg, censure not Torna), ‘Ro chuala ar thagrais a thaidhg’ (I have listened to your arguments, Tadhg), ‘Ná brosd mise a Mhic Dáire’ (Provoke me not, o son of Dáire), and ‘An gcluine mé a Mhic Dáire’ (Do you hear me, son of Dáire?). However, it is for writing a biography of Red Hugh O'Donnell that Ó Cléirigh is most famous. This work, Beatha Aodha Ruaidh Uí Dhomhnaill (The life of Red Hugh O'Donnell) was compiled sometime after 1616 and perhaps as late as 1627. A major Renaissance biography, written in an artificially archaic style using many long-obsolete words, it remains an important Gaelic source for the Nine Years’ War. Between 1632 and 1636 it was used as a source by the Four Masters, who referred to it as ‘the book of Lughaidh Ó Cléirigh. From one thousand five hundred eighty-six, to one thousand six hundred two’. Other works attributed to Ó Cléirigh include an elegy on Baothghalach Mac Aodhagáin. In 1643 Mícheál Ó Cléirigh, to whom he was distantly related, referred to Lughaidh Ó Cléirigh as one of the four most learned people in Ireland in his time.
There is no definitive evidence for his date of death, but it seems likely that he was dead by 1630 when the Four Masters began their work. Nothing is known of his wife, but his son Muiris cooperated with Mícheál Ó Cléirigh by providing access to manuscripts which he had inherited.