Thomas Sexton (1848–1932) was an Irish journalist, financial expert, nationalist politician and Member of Parliament (MP) in the House of Commons of the United Kingdom of Great Britain and Ireland from 1880 to 1896, representing four different constituencies. He was Lord Mayor of Dublin 1888–1889.
He was born at Ballygannon, County Waterford, where he attended the local CBS school. He became a leader-writer on The Nation newspaper and a member of the Parnellite Irish Parliamentary Party.
He was first elected MP for County Sligo in the 1880 general election, for South Sligo in the 1885 general election, then for Belfast West in the 1886 election and for North Kerry in the 1892 election. He was a cosignator of the No Rent Manifesto issued in 1881. He was regarded as one of the finest orators of the Irish Party, but handicapped by a querulous temperament. Following the party split over Parnell's leadership, he sided with John Dillon's anti-Parnellite faction, then in 1896 retired from parliamentary politics, disgusted at the bitter factionalism following the failure of the second Home Rule bill.