| Honorific-Prefix: | The Right Honourable |
| The Earl of Clancarty | |
| Order1: | President of the Board of Trade |
| Term Start1: | 29 September 1812 |
| Term End1: | 24 January 1818 |
| Monarch1: | George III |
| Primeminister1: | The Earl of Liverpool |
| Predecessor1: | The Earl Bathurst |
| Successor1: | Hon. F. J. Robinson |
| Birth Date: | 1767 5, df=yes |
| Death Place: | Kinnegad, County Westmeath |
| Nationality: | British |
| Party: | Tory |
| Alma Mater: | St John's College, Cambridge |
| Spouse: | Henrietta Margaret Staples (c. 1770–1847) |
Richard Le Poer Trench, 2nd Earl of Clancarty, 1st Marquess of Heusden (19 May 1767 – 24 November 1837), styled The Honourable from 1797 to 1803 and then Viscount Dunlo to 1805, was an Anglo-Irish peer, a nobleman in the Dutch nobility, and a diplomat. He was an Irish, and later British, Member of Parliament and a supporter of Pitt. Additionally he was appointed Postmaster General of Ireland, and later, of the United Kingdom.
Clancarty was the son of William Trench, 1st Earl of Clancarty and Anne, daughter of Charles Gardiner and his seat was Garbally Court in Ballinasloe, East County Galway where he was associated with the Great October Fair.[1] His brother was Power Le Poer Trench (1770–1839), archbishop of Tuam. He was educated at Kimbolton School and St John's College, Cambridge.
Trench represented Newtown Limavady in the Irish House of Commons from 1796 to 1798. He sat further for County Galway from 1798 to a short time before the Act of Union, when he was replaced by "Humanity Dick" Martin.
He was credited with resolving various border disputes in Holland, Germany and Italy at the Congress of Vienna, 1814–1815, and in his role as Ambassador to the Netherlands. For his service as ambassador to The Hague, he was awarded the hereditary title of Marquess of Heusden in the peerage of The Netherlands on 8 July 1815[2] by William I of the Netherlands, following the defeat of Napoleon in Brabant, in that same province's southern reaches. Trench was elected one of the 28 representative peers of Ireland on 16 December 1808. His seat in the House of Lords became hereditary when he was created Baron Trench (4 August 1815) and Viscount Clancarty (created 8 December 1823), in the Peerage of the United Kingdom, his older peerages being Irish peerages. He was a Commissioner for the Affairs of India and Custos Rotulorum of County Galway.
Between 1807 and 1809 Trench was one of the joint Postmasters General of Ireland[3] and he was appointed Postmaster General of the United Kingdom being one of the last joint holders of that office from 1814 to 1816.[4]
On 6 February 1796 he married Henrietta Margaret Staples, daughter of John Staples and Harriet Conolly. They had the following children:
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