Crosbie, Thomas (d. 1694), soldier and politician, was the eldest son of David Crosbie of Ardfert, a protestant planter whose family had moved to Kerry in the early seventeenth century. His mother (d. 1628), whose name does not survive in the records, was a daughter of John Steere, protestant bishop of Ardfert. His father sat in the 1634 and 1640–41 parliaments for the borough of Ardfert, and acted as governor of Kerry during the 1640s under Murrough O'Brien (qv), Lord Inchiquin; in November 1649 he surrendered the strategic town of Kinsale to the Cromwellians, and managed to retain his lands during the interregnum. Thomas Crosbie served as an ensign in the army of the English parliament, rising eventually to the rank of lieutenant in a troop of horse. After the restoration Charles II included Crosbie, who inherited the family estate in 1658, in the general pardon granted to supporters of the parliament. Appointed high sheriff of Kerry in 1661, he held the position until replaced by his eldest son, David, in 1683. During the 1661 election for the Irish parliament Crosbie supported the candidature of his brother-in-law, Richard Chute, and refused to return John Blennerhasset of Ballyseedy, who had received a clear majority of the votes. Summoned to appear before parliament as a result, he was publicly rebuked for this dereliction of duty and forced to apologise to Blennerhasset.
On 1 May 1664 James Butler (qv), duke of Ormond, appointed Crosbie, Chute, James Nagle, and Robert Southwell (qv) to manage his affairs in Cork and Kerry. This connection with the powerful Butler family greatly benefited Crosbie, who later received a knighthood for his services. In 1678, during a wave of anti-popish hysteria, he acted as a commissioner for disarming catholics in Co. Kerry, and in early 1681 was seeking (unsuccessfully, it seems) to purchase a new military commission. Crosbie also intended to rebuild the ruined cathedral in Ardfert, and actually purchased the timber for this project, but the outbreak of war in 1689 postponed any work indefinitely. Crosbie proved an ardent supporter of James II (qv), accepting a position in the Jacobite army on 27 July 1689, and he was one of only six protestants to attend the parliament in Dublin that year. After the defeat of James, however, the Crosbie family quickly reconciled themselves to the new Williamite regime, and Thomas retained his estates until his death in late 1694.
His first marriage to Bridget, daughter of Robert Tynte of Co. Cork, produced six children, including his heir David, whose grandson eventually became earl of Glandore. His second marriage to Ellen, daughter of Garrett Fitzgerald of Ballynard, Co. Limerick, proved short-lived and childless, and finally he married (1680) Elizabeth, daughter and coheir of William Hamilton. His eldest son David married Elizabeth's sister Jane on the same day, and the dual marriage agreement settled part of the Crosbie family estate on the eldest son of Thomas's third marriage. This son, also called Thomas, followed the family tradition with his election as MP for Co. Kerry (1709) and appointment as high sheriff of the county (1712, 1714).