King, Sir John (d. 1676), 1st Baron Kingston , army officer and landowner, was the eldest son of Sir Robert King (qv) (d. 1657) of Boyle Abbey, Co. Roscommon, and his first wife Frances (d. 1638), daughter of Henry Folliott, Baron Folliott of Ballyshannon. After the outbreak of the 1641 rebellion in Ireland, the Kings held Boyle Abbey as a protestant enclave. In 1642 Sir Robert travelled to London where he remained, serving parliament, for much of the rest of the 1640s. John was left to command the garrison at Boyle Abbey, but his position was challenged by a Major Ormsby; the matter was resolved in 1643 when James Butler (qv), marquis of Ormond and royalist lord lieutenant of Ireland, confirmed John in his command. In August that year, when the catholic Ulster army camped near Boyle, King and his forces surprised the Irish, killing 160 men.
In July 1649 King was in London, where parliament agreed to raise a regiment for him with which to participate in the reconquest of Ireland. By then a major in the army, he probably accompanied the expeditionary force, under the command of Oliver Cromwell (qv), that sailed from England to Ireland in September 1649. That winter he campaigned with Robert Venables (qv) in Ulster. At the battle of Lisnegarvey in Co. Down on 6 December 1649 he positioned his men at the top of a pass through which defeated royalists were likely to flee and killed around 400 of them. On 21 June 1650 he fought at the battle of Scarifhollis in Co. Donegal, where the parliamentarians destroyed the Ulster army; two days later, he captured the commander of the Ulster army, Heber MacMahon (qv), bishop of Clogher, near Clogher, and hanged him on the orders of his superiors. In 1651–2 he campaigned in Connacht, where the remnants of Irish resistance were mopped up.
By the end of 1652, however, King was increasingly discontented with the Cromwellian regime. As a member of the conservative landed gentry, he disliked the political and religious radicalism of the new authorities, and probably resented the favour enjoyed by his local rival Charles Coote (qv). He was particularly infuriated by the government's plans to hand over some of his lands in Sligo and Roscommon to transplanted catholic landowners. In December 1652 he publicly berated parliamentary officials for the heavy taxes they were levying on his lands. Hence, on 26 May 1654, he wrote secretly to Ormond, then in exile on the continent, pledging his allegiance to the royalist cause. Later in the summer he confidently declared that he could seize Galway and perhaps even all of Connacht in the event of a royalist uprising. This behaviour contrasted markedly with that of his father, who acted as a high-ranking government official until his death in 1657. The Kings may well have been hedging their bets.
After the regiment in which he served was disbanded in August 1653, King acted as a commissioner for surveying lands in Sligo and as commissioner of the peace in Cork in 1654. He spent the rest of the 1650s on the fringes of power; he impressed Henry Cromwell (qv), chief governor of Ireland (1657–9), who knighted him in 1658 and recommended (unsuccessfully) that he be appointed muster master of the Irish army. Away from politics, he was engaged in dramatically increasing his estates. Both he and his father purchased large numbers of debentures from English soldiers; most of these debentures appear to have been realised by 1659, providing the Kings with extensive estates throughout Ireland. In 1658 King married Catherine Fenton, daughter and heir of Sir William Fenton of Mitchelstown, Co. Cork, and Margaret Fitzgibbon. This marriage gave King control of a vast Munster estate centred on Mitchelstown.
In December 1659, worried by the growing political instability in England, a group of conservative protestant army officers seized control of the Irish government. King does not appear to have played a major role in this coup, but by January 1660 he was a member of the council of officers that effectively governed Ireland in early 1660. He strongly urged his colleagues to support the restoration of the monarchy, and the king and his advisers regarded him as staunchly royalist. In March 1660 Charles II promised King that he would send him a supply of arms and ammunition if needed. King sat as a member for Boyle Abbey in the 1660 Irish convention and in May was chosen by the army to present an address in London broadly supporting the return of the monarchy.
After Charles II's return to London, King was knighted on 5 June 1660, created Baron Kingston on 4 September 1660, sworn of the Irish privy council in late December 1660, appointed commissary general of the horse in Ireland on 11 May 1661, and made joint president of Connacht on 2 April 1666; in the last post he was occupied with campaigns against tories. He was also restored to his military command, serving first as captain in Coote's regiment (1661–72) and then as colonel of his own regiment of cavalry (1672–5).
About 1661 King was forced to surrender some of the lands he had received for his debentures so that they could be restored to their original owners. After a long delay, in 1664 he was partially compensated for these losses by grants of lands in Kildare and Limerick. He retained the bulk of the lands he had acquired during the 1650s, making him one of the most powerful landowners in the kingdom, and in 1663 he was described as one of the most influential figures in the Irish parliament. From 1660 he resided at Mitchelstown, handing over the administration of his Boyle estates to his younger brother Sir Robert King. He also had an estate at Bidston Hull in Wirral, Cheshire. He died in March 1676 and was succeeded by his son Robert (d. 1693).