William Ulick Tristram St Lawrence, 4th Earl of Howth KP (25 June 1827 â 9 March 1909) was an Irish peer, styled Viscount St Lawrence until 1874. He became Earl of Howth in 1874 on the death of his father, Thomas St Lawrence, 3rd Earl of Howth, and was appointed a Knight of the Order of St Patrick on 8 May 1884. His mother was Thomas's first wife Lady Emily de Burgh, daughter of John de Burgh, 13th Earl of Clanricarde.
He became a captain in the 7th Queen's Own Hussars 1847. He was High Sheriff of County Dublin in 1854. He sat in the English House of Commons as a Liberal MP for Galway Borough from 1868 to 1874. He was State Steward to the Viceroy of Ireland from 1855 to 1858.
Lord Howth suffered from tuberculous that he believed to have had "inherited from his mother" and often wintered at Pau from 1863 due to its milder climate. For several years he served on the kennel committee of the Pau Hunt and as master of the Pau hounds during the 1878-1879 season. He was an advocate for traditional fox hunting, opposing the hunting of animals that had been captured for release as bagmen. He also encouraged the popular and more difficult sport of drag hunting be coursed and accessible to less-abled riders.
He died at a Bournemouth hotel aged 81, unmarried. The family titles became extinct on his death as he had no male heir.