William Henry Fortescue, 1st Earl of Clermont KP (5 August 1722 – 30 September 1806) was an Irish peer and politician.
He was the eldest son of Thomas Fortescue (1683–1769), the MP for Dundalk. His younger brother was James Fortescue, MP and Privy Counsellor.
He served as High Sheriff of Louth in 1746. He represented Louth in the Irish House of Commons from 1745 to 1760 and subsequently Monaghan Borough from 1761 to 1770. In 1768 he briefly sat as Member of Parliament for Dundalk before opting to sit for Monaghan Borough, for which he had also been elected.
He was appointed Governor and Custos Rotulorum of County Monaghan for life in 1775, standing down just before his death in 1806. He was created Earl of Clermont in 1777 and a Knight Founder of the Order of St Patrick on 30 March 1795.
He had married Frances Cairnes Murray, daughter and coheiress of Colonel John Murray, MP for County Monaghan. They had an only daughter, Louisa. On his death his Earldom of Clermont and 1770 Barony of Clermont became extinct whilst his Viscountcy and 1776 Barony of Clermont were inherited by a nephew, William Charles Fortescue, who had been MP for Louth (Parliament of Ireland constituency) and then Louth (UK Parliament constituency) since 1796.