Mac Liag, a bard of Brian Boru
is the reputed author of an ancient manuscript entitled Cagadh Gaedhil re Gallaibh (the War of the Gaeil with the Foreigners ie the Norwegians and Danes).

Bishop John O'Lee or O'Ladaigh died c. 1280
a Dominican, John O'Lee or O'Ladaigh, of Straide Abbey, was made bishop of Killala in 1253.
He adjudicated in a dispute between the sees of Cashel and Lismore in 1263, and he was fined for failing to attend the Parliament in Castledermot.
A letter from the Vatican, dated 20 February, 1264, gave him permission to resign, owing to the fact that he was illegitimate, and had no dispensation from the Pope to hold office. As seems to have been common practice with the clergy of the time, he ignored this unwelcome letter, and gave rise to scandal, as a result.
He died, as bishop, apparently, in 1275, (or possibly in 1280, as there is a man with a similar name holding his office until 1280 according to the Four Masters, and a replacement was appointed in 1281).

Illann Mac an Leagha, and his sons Maelechloinn, Eoghan and Connla
Its occurrence in the Annals of Loch Cé, is the only record in the annals of this surname. Maelechloinn's document, dated from 1512, reference number Ms 15 in the King's Inns Library, describes himself as ollav to the two Mac Donnchaidh in northern Connacht. Trinity College Ms D.4.3 has the signatures of Maelchloinn and Connla, and Maghnus, son of Giolla na Naemh Mc Liagh, a possible family member.
Illann may possibly be identified with Uilliam Mac an Leagha (fl 1450) of north Roscommon, to whom has been credited the translations from English to Modern Irish of Stail Ercail (History of Hercules), Betha Mhuire Eigiptachdha (Life of Mary of Egypt), and the Irish version of Guy de Warwick.

Morogh O'Lee or O'Ley
We have no dates for this man's life, except that his lands were confiscated under the Act of Settlement, and in 1663 his petition for their return was rejected.
Roderick O'Flaherty mentions him in relating a story from 1668, on Inismore, Aran, and Hy-Brazil, a mythical land off the west coast. Seven or eight years later, to make a living, he began to practise 'chisurgery and phisick' despite having no prior knowledge of such crafts, apart from the family tradition of being hereditary physicians in Connacht.
But in his defence, he apparently owned and may have read the Book of the O'Lees of O'Brazil (Hi-Brazil), a medical treatise in Irish and Latin, which is in the Royal Irish Academy manuscript number Ms 454.