William Thomas Le Poer Trench, 3rd Earl of Clancarty, 2nd Marquess of Heusden (21 September 1803 – 26 April 1872), styled Viscount Dunlo between 1805 and 1837, was an Irish peer, as well a nobleman in the Dutch nobility.
He was educated at St John's College, Cambridge.
[1] Trench was born in Castleton, County Kildare, Ireland the son of Richard Trench, 2nd Earl of Clancarty and Henrietta Margaret Staples.
On 8 September 1832, he married Lady Sarah Juliana Butler.
They had six children.