William Charles Fortescue, 2nd Viscount Clermont (12 October 1764 – 24 June 1829), was an Irish politician.
Fortescue was the son of James Fortescue and Mary Henrietta Hunter, daughter of Thomas Orby Hunter, of Crowland Abbey, Lincolnshire. William Fortescue, 1st Earl of Clermont, was his uncle.
He served in the British Army, reaching the rank of lieutenant. In 1796 he was returned to the Irish House of Commons for County Louth (succeeding his brother Thomas James Fortescue), a seat he held until 1800, when the Irish Parliament was abolished on the formation of the Union. He was instead returned to the British Parliament for County Louth, where he remained until 1806. The latter year he succeeded his uncle Lord Clermont as 2nd Viscount Clermont according to a special remainder in the letters patent. This was an Irish peerage and did not entitle him to an automatic seat in the English House of Lords although he was forced to resign his seat in Parliament as Irish peers were barred from representing Irish constituencies in the House of Commons.
Lord Clermont died at Ravensdale Park, County Louth, in June 1829, aged 64. He was unmarried and the viscountcy died with him. The Clermont title was revived in 1852 when his kinsman Thomas Fortescue was made Baron Clermont.