Thomas Allan (1725–1798) was an Irish politician.
Allan sat in the Irish House of Commons as the Member of Parliament for Killybegs between 1768 and 1776. In 1773 he was appointed Commissioner for Revenue in Ireland. He then represented Naas from 1777 to 1783. Between 1778 and 1785 Allan served as Commissioner of Customs in England.
- John Beresford, The Correspondence of the Right Hon. John Beresford (Woodfall and Kinder, 1854), p.4. (Retrieved 22 February 2016).