Thomas Harbison (1864 - 22 November 1930) was an Irish nationalist politician.
After growing up in Cookstown, Harbison studied at St Malachy's College in Belfast. He became active in the Irish Parliamentry Party, acting from 1906 until 1910 as the election agent for William Redmond and Thomas Kettle. In 1911, he was elected to Tyrone County Council.
After attending the Irish Convention, he was elected to Westminster at the East Tyrone by-election, 1918, after Redmond resigned it to contest Waterford City. At the 1918 UK general election, Harbison was elected in North East Tyrone.
At the Northern Ireland general election, 1921, Harbison was elected on an abstentionist platform in Fermanagh and Tyrone. In 1922, he was elected in the Westminster constituency of Fermanagh and Tyrone for the Nationalist Party. He stood down from the Westminster seat at the 1924 election, and in 1927 took his seat at Stormont. In 1929, he stood down from his Stormont seat, but was again elected to Westminster, serving until his death a year later.