Kirwan, Thomas (1772–1852), Dublin merchant and catholic politician, was probably a son of Thomas Kirwan (d. 1807?) who was also in trade in Dublin and a catholic politician. Thomas Kirwan the elder appears in Wilson's Dublin Directory as a merchant successively in Cutpurse Row (1767–9), Usher's Quay (1773–84), James's St. (1787–99), Townsend St. (1800–2) and Abbey St. (1804–7); he may have married twice, as he married Ealce Donnely (sic) in 1761 but in 1778 his wife's name was given as Mary; he was a founder-member of the Dublin chamber of commerce (1783) but shortly after went bankrupt (1784) and later became a brewer. He was a member of the Catholic Committee (1779–82) and was presumably the Thomas Kirwan whose name appears as a member nine years later (1791). Likewise it is presumed that he was the Thomas Kirwan who attended the Catholic Convention as a representative of Waterford city and county (1792–3) and was said then to be of Carrick-on-Suir. Thomas Kirwan the younger appears in the Dublin directories as a merchant in Fleet St. (1800–25) and Abbey St. (1826–52).
He became a public figure as a result of an attempt in 1811 to revive the Catholic Convention. With others he attended a meeting in Liffey Street Chapel held for the purpose of appointing delegates from St Mary's parish to a planned representative convention that was to prepare a petition to parliament for the removal of catholic disabilities (31 July 1811). Kirwan and several others present were consequently arrested (9 August). With Dr Edward Sheridan he was arraigned before the court of king's bench on a charge of contravening the Convention Act, passed in 1793 to prohibit representative assemblies (November 1811). Sheridan was tried and acquitted. Kirwan's trial (27–9 January 1812) resulted in a conviction. Kirwan, whose defence was led by Peter Burrowes (qv), was fined one mark and discharged (6 February). The verdict and sentence satisfied the government and did not deter the catholic leaders, who then formed themselves into the Catholic Board.
Kirwan married Mary Sweeney of Drumcondra and is said to have had with her 16 children; the family lived at Wellpark, Drumcondra, for many years. He died, a justice of the peace, in Fitzwilliam Sq. South on 4 June 1852 and was buried in the O'Connell circle at Glasnevin cemetery. Among his possessions were the minutes of the Catholic Committee, 1773–92, which his son John (d. 1881) passed down to Thomas's granddaughter Mary Catherine Woods (d. 1913), mother of the Dublin solicitor Seán Ó hUadhaigh (qv), who made them available to the historian R. Dudley Edwards (qv) for publication.