Barnewall, Patrick (c.1584–c.1660), politician, was eldest son of John Barnewall of Kilbrew and his wife Eleanor, daughter of Christopher Seagrave of Dublin. John died in 1590, and Eleanor remarried successively Edward Aylmer, John Cheevers, and Thomas Fitzwilliam. Patrick married first Eilís (Ellis) Barnewall of Crickstown; secondly Cecily, daughter of William Fleming, Lord Slane; and finally, sometime before 1633, the widow (whose name does not survive) of Jasper Hurlestown of Drogheda. These multiple marriages created an extensive network of personal connections, which, combined with the family's traditional prominence within the Pale region, enabled Barnewall to play a leading political role both locally and nationally. He owned extensive properties in the baronies of Ratoath and Duleek, and served as sheriff of Meath on three occasions between 1610 and 1622; his son Richard sat as MP for the borough of Swords in the 1634 parliament. The borough of Trim elected Barnewall to parliament in 1640, where he acted as a leader of the catholic opposition in the commons.
After the outbreak of the Ulster rebellion in October 1641, Barnewall and other MPs formed a committee, hoping to negotiate with the insurgents. The action of the lords justices, however, proroguing parliament and sanctioning indiscriminate attacks on Irish catholics, undermined this peace strategy. Shortly afterwards Barnewall attended meetings at Crofty and Tara, helping forge an alliance between the Pale nobility led by Nicholas Preston (qv), 6th Viscount Gormanston, and the Ulster Irish, represented by Barnewall's son-in-law, Rory O'More (qv). Nominated on to a council of war, along with his stepson, Sir Richard Barnewall (qv) of Crickstown, Patrick Barnewall successfully raised 100 men from his locality to join the rebel army. In early 1642 Gormanston sent him on a successful mission to procure powder and weapons in Wexford town. The publication of the king's proclamation (March), condemning those risen in arms, convinced Barnewall and a number of prominent catholics to surrender to the royalist commander, James Butler (qv), 12th earl of Ormond. His subsequent torture by the lords justices almost certainly prevented further desertions from the rebels' ranks.
Formally expelled from the commons on 22 June 1642, Barnewall successfully petitioned for his release from jail in 1643, and found employment raising funds for the royalist army in Ireland. By early 1646 he was accorded once more the privileges of a member of parliament, although no records survive of his attending the commons at this time. After the rejection of the first Ormond peace treaty by the supporters of the papal nuncio, Gian Battista Rinuccini (qv), Barnewall travelled to Kilkenny. He joined the confederate association, attending the general assembly in January 1647, where he supported the faction seeking to negotiate a new deal with the royalists. During his absence from Dublin, the administration ordered a fresh election for his parliamentary seat. After the signing of the second Ormond peace treaty (January 1649), Barnewall raised troops for the royalist army in Meath, and examined Randal MacDonnell (qv), marquis of Antrim, on his links with the English parliament. The date of his death is unclear (most likely c.1660), but in March 1661 the king ordered that Barnewall's heir, Simon, be restored to the family lands, judging his father as one who had lived inoffensively since the beginning of the rebellion.