MacMurrough Kavanagh, Domhnall (d. 1632), king of Leinster, was the elder of the two sons of Donnchadh Kavanagh, lord of the Art Boy Kavanaghs; he became the last king of Leinster. In the traditional order, among the leading MacMurrough Kavanaghs, the Art Boy Kavanaghs were probably the least powerful. Their lands lay mainly to the north of Enniscorthy in the Blackstairs mountains, in close proximity to the English of Wexford. Domhnall's father seems to have died while the boy was still young, for Thomas Stukeley (qv), the seneschal of Wexford, took him into his care. In 1568 Stukeley left Ireland for Spain, taking Domhnall with him, which accounts for his sobriquet ‘Spainneach’ (the Spaniard). Domhnall probably returned to Ireland in the mid-1570s, when he became a leading lord of the Art Boy Kavanaghs; he later married his cousin Eleanor Kavanagh (d. in or after 1633), daughter of Brian MacMurrough Kavanagh (qv) and Elizabeth O'Byrne (d. in or after 1608). He gradually moved into the circle of Fiach MacHugh O'Byrne (qv), lord of Crioch Raghnuill, with whom he made an alliance and a firm friendship. In November 1579 it was reported that Domhnall had received a letter from Gerald Fitzgerald (qv), 15th earl of Desmond, encouraging him to fight for the catholic faith.
The alliance between Domhnall and O'Byrne received its first serious test in 1580. On 10 April Domhnall led a raiding party into the southern Wexford baronies of Shelbourne and Bantry. They were attacked by Sir Thomas Masterson (d. 1590), seneschal of Wexford; Domhnall managed to escape but many of his men surrendered and fifty of them were hanged by Masterson. Domhnall sought the help of Thomas Butler (qv) 10th earl of Ormond, whose protection his men had enjoyed, but Ormond's outraged demands that punitive action be taken against the seneschal were ignored by the Dublin council. In April, at Domhnall's instigation, the Art Boy Kavanaghs and Gerald Odhar O'Byrne of Clone (d. in or after 1601) plundered the seneschal's possessions around Ferns before returning to the safety of Ormond's lordship of Arklow. Two months later Fiach O'Byrne joined Domhnall to wreak further havoc on Wexford in the course of a powerful raid, and the two remained together throughout much of the Leinster war of 1580–81.
In summer 1581 Lord Deputy Arthur Grey (qv), Baron Grey de Wilton, stepped up the pressure on Domhnall, campaigning vigorously throughout his densely forested heartland in the Blackstairs mountains. The Art Boy Kavanaghs sued for peace, angering O'Byrne, who in July raced for many miles to prevent their submission. On 23 August Grey authorised Sir Henry Harrington (d. 1605), the seneschal of the O'Byrne and O'Toole countries, to accept O'Byrne into mercy on condition that he disband his forces. This allowed Domhnall finally to come to peace: he became a protected man in October before gaining his pardon on 19 May 1582; he was again pardoned on 19 April 1585 for unspecified offences and was required to answer the sessions of the assize court. It was reported on 6 January 1586 that Domhnall and his brother Cathaoir killed James Dullerde, the murderer of Bishop Nicholas Walsh (qv) of Ossory; but he managed to stay on the right side of law between 1586 and 1588, lodging his pledges in Dublin Castle, and was pardoned yet again on 21 February 1593.
Domhnall continued to figure prominently in O'Byrne's plans and was elected king of Leinster at some time in the early 1590s. Their close alliance probably had much to do with the attempts of Sir Henry Wallop (qv) to plant the lands around Enniscorthy, and it provided support for Domhnall's claims to lands at Ferns and Clohamon. War broke out in Leinster in late 1594. On 2 March 1596 a commission was established to inquire what lands belonged to Domhnall after he had offered to hold them of the crown, and on 24 March Domhnall and his brother Cathaoir were bound to the peace. But O'Byrne soon reestablished his influence over Domhnall, and on 25 June it was reported that Domhnall and Uaithne O'More (qv) of Laois (d. 1600) were travelling to a conference with him in the forests of Coolattin. There Piers Butler (qv) of Cloghgrenan took an oath of friendship to Domhnall as king of Leinster before being admitted to O'Byrne's presence.
Throughout the summer Domhnall and his forces supported O'Byrne's campaign of intimidation against the garrison of the fort of Ballinacor, helping to take it on 9 September. Some time soon afterwards, Domhnall committed himself fully to O'Byrne's cause, taking an oath to him. In a campaign with O'Byrne and Barnaby O'Toole (qv), Domhnall threatened to besiege Castlekevin, and burned throughout east Wicklow and south Dublin. After the killing of O'Byrne on 7 May 1597, Domhnall realised that the military situation in Leinster was now desperate. With Phelim O'Byrne (qv), Reamain O'Byrne (d. in or after 1642), Uaithne O'More, and Brian Riabhach O'More (qv), he travelled to Ulster to the protection of Hugh O'Neill (qv), 2nd earl of Tyrone. He seems to have returned briefly to Leinster in September with O'More before returning finally about January 1598, when both he and Phelim agreed to respect Tyrone's truce with the government; but he was back at war that summer, aiding O'More against the Butlers. In October he and O'Byrne burned much of Kilkenny and Ossory and in the same month the two attended a conference with Edmund Butler (qv), 2nd Viscount Mountgarret, to plan further hostilities against the government in 1599, committing themselves to their cause after taking the sacrament. This alliance was sealed with the marriage of Domhnall's son to Mountgarret's daughter. In December 1598 it was reported that Domhnall had resigned his kingship of Leinster briefly, in favour of the rank of general.
1599 and 1600 saw a long struggle between the English and the catholic forces, punctuated by passages of peace. The catholic forces won victories at the Pass of the Plumes on 17 May and at Deputy's Pass twelve days later, but their triumph was overturned when Robert Devereux (qv), earl of Essex and lord deputy of Ireland, skirmished with Domhnall near Enniscorthy before routing him on 29 June outside Arklow. Soon afterwards Domhnall submitted again, probably in August, but he did not remain at peace for long, for in September, with 300 or 400 followers, he attacked the English of Wexford. Within days he offered to parley with Essex and agreed another peace, yet he returned to the fray in 1600, burning much of southern Wexford in April before attacking Kilkenny in June. He again offered to submit, this time to Charles Blount (qv), Lord Mountjoy, lord deputy of Ireland, but his advances were rejected, and on 21 July English troops plundered his lands and livestock. The killing of Uaithne O'More on 11 August by Mountjoy's troops was a disaster for the Leinstermen and demoralised Domhnall, undermining his will to fight. As Mountjoy closed in, Domhnall wrote secretly to Ormond on 19 August seeking to return to his allegiance. On 24 August Mountjoy's army was confronted by a catholic force of 2,560 at the pass of Cashel but, before the forces could engage, Domhnall, the commander of the catholic right wing, approached the English army and submitted on his knees, requesting twelve days’ protection for himself and O'Byrne. When this was granted he drew off his force, deserting his comrades to defeat.
Resolved not to fight against the government again, Domhnall made a formal submission to the Dublin council with some of the O'Mores of Laois before 20 September. At this ceremony also he asked that his claims to lands in Wexford be considered. The government now sought to pacify the disaffected catholic Leinster aristocracy and detach them from Tyrone. Domhnall was granted his pardon on 15 May 1601, and the O'Byrne brothers with the O'Tooles of Castlekevin were granted theirs in July. It was said, though, that Domhnall again grew haughty towards the English after the Spanish landed at Kinsale in September 1601; intent on keeping him at peace, the government pardoned him again on 16 October, but he returned to war briefly before submitting for the last time in April 1602.
After the death of Elizabeth, Domhnall was awarded a pension from James I on 22 August 1603 (he later sold it to Sir Roger Jones on 8 August 1615). He remained loyal, but did not hesitate to assert his rights – he killed a robber who raided his lands in February 1604 – and also kept close contact with his former comrades in arms: according to Sir John Davies (qv), writing on 19 April, a meeting of Domhnall, the O'Byrnes, and Tyrone in Carlow nearly ended in a sword fight. The government kept a close watch on him. In May 1608 Ormond reported that Domhnall had held a gathering of the MacMurrough Kavanagh leaders on Good Friday and suggested that he was planning trouble; asked to account for his actions Domhnall replied that they had met to venerate a piece of the Holy Cross that had arrived from Rome. He proved his loyalty by serving as a justice of the peace later that year. Despite the outward appearance of submission, he was still in contact with the exiled Tyrone, and received a letter from him in 1610.
Although the plantation of Wexford reduced Domhnall's lands somewhat, he managed to convey his property to his son Sir Morgan Kavanagh (d. 1643). The last king of Leinster died in 1632, leaving six offspring.