O'Hanlon, Sir Eochaidh (Oghy) (c.1560–1623?), lord of Orior, was the eldest of five sons; his parents are not identified and the date of his succession to the lordship of Orior in Armagh is uncertain, but he was important enough to be considered a worthy match for the sister of the O'Hanlons’ powerful ally Hugh O'Neill (qv), 2nd earl of Tyrone; Eochaidh's daughter was later to marry Henry O'Hagan, a prominent member of the earl's foster family, and Eochaidh's son and heir, Eochaidh Óg O'Hanlon, married the sister of Sir Cahir O'Doherty (qv) of Inishowen. Eochaidh had been lord of Orior for some years when in 1587 Lord Deputy Sir John Perrot (qv) attempted to check the power of Tyrone by persuading Eochaidh to surrender all his territory in Upper and Lower Orior to the crown; he received it back through regrant and thereafter held it by knight service. As part of the agreement Eochaidh gave up his traditional title and was knighted. By Sir Eochaidh's letters patent of 1 December 1587, his property would pass upon his death to his son, and should Eochaidh Óg die without issue it would pass to Sir Eochaidh's three natural sons and their issue. His satisfaction with this agreement is suggested by his having travelled to Dublin in June 1588 to say goodbye to Perrot, who was returning to England; and he even served as sheriff of Armagh in 1592–3.
For several years O'Hanlon's situation was secure, but by the mid-1590s there were rumours of unrest in Ulster. The focus of the government's suspicion was Tyrone, Sir Eochaidh's brother-in-law. In March 1594 Sir Henry Bagenal (qv) (d. 1598), Tyrone's mortal enemy, reported that Magennis and Sir Eochaidh had, reluctantly, recognised the earl's overlordship, and in October 1594 both agreed to maintain large contingents of Tyrone's troops in their lordships. By July 1595 Sir Eochaidh had resumed his allegiance to the government and taken up the office of hereditary royal standard bearer north of the Boyne; while carrying the standard he was shot in the foot in an ambush in the pass of Moyry, which left him with a permanent limp. However, Tyrone's power proved too much for him and he changed sides again; from 1596 he was firmly attached to Tyrone, who on 3 December 1597 granted him and other Ulster nobles protection.
At the end of 1597 a truce was agreed between Tyrone and the government, and in March 1598 Sir Eochaidh travelled with Tyrone to meet the lord deputy, and submitted on his knees with Magennis and MacMahon. He maintained his loyalty to the regime through the brutal campaign of early 1600 waged by Lord Deputy Charles Blount (qv) (d. 1606), Lord Mountjoy, his service with whom led to a false report of his death in fighting at the pass of Carlingford on 17 November. Although in October and November 1601 Tyrone exerted considerable pressure upon Sir Eochaidh and his neighbour Sir Toirdhealbhach O'Neill (qv) to join him on the march to Kinsale, they steadfastly refused. Sir Eochaidh is next heard of in February 1605, when Sir Arthur Chichester (qv) sought his pardon for an unspecified incident.
His reputation as a loyalist suffered considerable damage in spring 1608 when Eochaidh Óg led a revolt, ostensibly in support of his brother-in-law Sir Cahir O'Doherty of Inishowen, but in reality to express his dissatisfaction with the political situation in Armagh and Ulster, and probably his anger against his father for his collaboration with the government. Eochaidh Óg was eventually shipped off in autumn 1609 to serve in the Swedish army against the Poles and after many adventures made his way to the Spanish Netherlands. In 1608 Sir Arthur Chichester described Sir Eochaidh as ‘an old, lame man, of weak judgement’, and claimed that he was ruled by his wife, Tyrone's sister. In October that year Sir Eochaidh was induced to surrender his lordship in return for an annuity of £80, a grant that was confirmed in December 1611 and again in 1623. It appears that the last Irish lord of Orior died some time in 1623 or shortly afterwards.