William Ulick Tristram St Lawrence, 4th Earl of Howth KP (25 June 1827 – 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.

He sat in the English House of Commons as a Liberal MP for Galway Borough from 1868 to 1874.

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