O'Hart, Eugene (d. 1603), catholic bishop of Achonry, was probably born in Carbury, Co. Sligo. His family served as retainers for the dominant local clan, the O'Connors of Sligo. He entered the Dominican order at Holy Cross, Sligo, where he made his profession and studied classical Greek and Latin writings. His ability impressed his superiors, who sent him to study at Salamanca and Paris. He remained in Paris for eight years, possibly during the 1550s, and there he became acquainted with protestantism, particularly Calvinism. On returning to Ireland, he was elected prior of Sligo, before being chosen by the clergy of Connaught to act as their procurator at the Council of Trent. He was in Rome by about the start of 1562 and was appointed bishop of Achonry at a papal consistory on 28 January 1562, being consecrated as such at Rome soon after. As well as his undoubted intelligence and ability, a key factor in his appointment was personal influence in the Sligo area. In recommending him for the bishopric, the papal emissary to Ireland, David Wolfe (qv), noted that O'Hart would be able to recover Achonry cathedral, then being used by local families as a fortress, for the church.
On 25 May 1562 he arrived at Trent in the Alps, with two other Irish bishops, to take his place in the council. A frequent contributor to debates, he spoke on a range of theological, moral, and ecclesiastical issues, and his views marked him as an exponent of the uncompromisingly militant brand of catholicism that was being forged at Trent. He spoke out against clandestine marriages and vigorously upheld the pope's absolute dominance of all ecclesiastical power, the doctrine of purgatory and the veneration of saints and holy images. Following the council's conclusion on 4 December 1563, he returned to Ireland and his bishopric.
For the rest of his life, he dedicated himself to enforcing the regulations laid down at Trent in his own diocese and beyond. He appears to have succeeded in possessing Achonry cathedral upon his return to Ireland. By 1586, English officials were referring to Achonry as O'Hart's town. In 1566 he helped convene a provincial synod for Connaught, which promulgated the decrees of Trent. Particular emphasis was placed on the stricter regulations governing marriages. O'Hart benefited from the fact that his diocese lay outside the control of the protestant government. Moreover, the authorities cultivated the dominant local lord within the diocese (and O'Hart's patron) Sir Donal O'Connor Sligo (qv) as a counterweight in the north-west to the more powerful O'Donnell clan. As a result, he was for long able to proceed with his duties without being subjected to government harassment.
However, this arrangement was threatened after royal forces established military dominance of the Sligo region during the early 1580s and even more so after the appointment of Sir Richard Bingham (qv) as president of Connacht in 1584. Eager to seize a personal estate in Sligo, Bingham deliberately rode roughshod over local sensibilities and, in summer 1585, arrested O'Hart who was imprisoned in Dublin Castle. During a meeting in June with the Church of Ireland primate John Long (qv), O'Hart allegedly admitted the errors of catholicism, renounced his bishopric and condemned the pope. It should be borne in mind that Long and the lord deputy of Ireland Sir John Perrot (qv) disapproved of Bingham's heavy-handedness in Connacht and were eager to employ O'Hart as an intermediary in order to prevent unrest in the western province. Most likely Long provided a falsified account of his meeting with O'Hart in order to justify Perrot's intention to release him. If O'Hart did renounce his faith, he was almost certainly being insincere. Having been freed, he helped to broker a peace treaty between the government and the Gaelic lords of Sligo on 3 September 1586. As part of this deal, the crown recognised O'Hart as bishop of Achonry and granted him the temporalities of his see. There was no mention of the oath of supremacy. In effect, the government agreed to turn a blind eye to O'Hart's catholic proselytising in return for his political loyalty.
In December 1591 the queen appointed Owen O'Connor (d. 1607), protestant bishop of Killala, as administrator of Achonry. However, O'Connor was an old friend of O'Hart and a probable crypto-catholic. He agreed to allow O'Hart a free hand in Achonry, in return for the payment of 180 marks a year. In the summer of 1593 O'Hart was in Munster conducting confirmation services. Much to the consternation of the local authorities, people flocked from all over the province to have their children confirmed. On being interrogated by Thomas Norris (qv), vice-president of Munster, at Mallow, he produced a licence, which indicated that he had sworn an oath of loyalty to the queen, and was released. However, he denied taking the oath of supremacy.
O'Hart does not appear to have played any role in the rebellion of Hugh O'Neill (qv), earl of Tyrone, against the crown, which convulsed Ireland from 1594 to 1603. Indeed, for most of his career, he eschewed politics, preferring to concentrate on his pastoral duties. Moreover, his local allies, the O'Connors of Sligo, were mortal enemies of Red Hugh O'Donnell (qv), Tyrone's close ally. Following the suppression of the rebellion in 1603, his relations with the government remained amicable. On 19 April 1603 he, as bishop of Achonry, was pardoned, along with other leading Sligo figures. He died later in the year, apparently aged 100 (although it is more likely that he had merely attained a great age, probably upwards of 80 years), and was buried in Achonry cathedral. He was the last Irish bishop to be formally recognised by both the papacy and the English crown.