John Thomas Foster of Dunleer (1747 – 10 October 1796), was an Irish politician.
He was the son of Rev Thomas Foster, Rector of Dunleer and Dorothy née Burgh.[1] Foster was elected member to the Irish House of Commons for Dunleer in 1776 and held this seat until 1783. Subsequently he represented Ennis until 1790.
Foster married 1776, Lady Elizabeth Hervey, the daughter of 4th Earl of Bristol; they separated 1781. After their separation, Elizabeth became mistress and later second wife of William Cavendish, 5th Duke of Devonshire. Together, they had two sons and a daughter: