King, Sir William (d. 1706), soldier and politician, was son of George King and his wife Grace Coleman; his maternal grandfather, Richard Coleman, was at one time chief remembrancer of the Irish exchequer. King saw service in Ireland in the 1640s, almost certainly in Munster. The details remain obscure, but though originally a royalist (at least nominally), he later defected to parliament. He settled in Ireland after the disbanding of his unit, conducting official duties throughout the 1650s and eventually owning land in six counties, having obtained it via the three official channels as soldier, adventurer's assignee, and purchaser. At some point he married Barbara Boyle, daughter of John Boyle, d. 1620, bishop of Cork, and a cousin of Roger Boyle (qv), Lord Broghill and later earl of Orrery. King became a close associate of the latter, and later rented property from him. He had two sons, George and John.
Having served at some point as sheriff of both Limerick and Clare, in 1656 King became mayor of Limerick; he would hold this post again later in life. In 1660 he subscribed to the 18 February declaration of the Munster officers for a free parliament, and was elected to the 1660 Dublin convention to represent Co. Limerick. He also subscribed to the 13 April declaration, pledging the army in Ireland to accept the authority of either the English parliament or the council of state. Knighted at the restoration, on 11 February 1661 King commanded a troop of horse, and was subsequently elected MP for Co. Limerick (1661–6). In December 1661, with Broghill's assistance, he was granted arrears for service before 5 June 1649, receiving forfeited lands in Limerick. He was sheriff again in 1665–6, and continued to obtain land. On 17 April 1672 he was made a captain of foot. Promoted to major (September 1672), he saw service in the Anglo–Dutch war, and was promoted to lieutenant-colonel (7 June 1673); in April 1674 he was granted a £150 pension in perpetuity. As governor of Limerick during the anti-catholic scares caused by the ‘popish plot’ of 1678, King took an active and assiduous role in improving fortifications and pursuing suspects, often in association with Orrery. But while he was well regarded, in October 1679 it was accepted that King would be relegated to deputy-governor should his post be requested by Richard Boyle (qv), 2nd earl of Cork and 1st earl of Burlington. In March 1681 he expressed concerns for the welfare of soldiers married to catholics, given that their dismissal was in hand. In 1685 King, by now a colonel of foot, left the army on the accession of James II (qv). During the Williamite war, he entertained Williamite officers at his house at Kilpeacon. Imprisoned during the second siege of Limerick, on 18 August 1691 he escaped, providing information to the Williamite army as it advanced on the city.
In 1692 King was constable of Limerick castle, and he was MP for Co. Limerick in both Williamite parliaments (1692–3, 1695–9), one of only a small number of MPs to have served before and after the Glorious Revolution. He signed the association for the protection of William III (qv) in 1696, and saw limited committee service in both parliaments. In 1699 he was deputy governor of Limerick. King died on 4 September 1706. As stipulated in his will, a monument was later erected in Kilpeacon church. King was a particular type of settler: one of the many experienced, middle-ranking figures who made possible the governance of the country, both as official administrators and as members of the various family interests – in this case that of the Boyles – that came to dominate much of Irish society at this time. King's eldest son George (1689–1722) later served as MP for Co. Limerick (1713–14) and Kilmallock (1715–22).