William Grimston, 1st Viscount Grimston (31 December 1684 – 15 October 1756), of Gorhambury, St Albans, Hertfordshire, was a British landowner and politician who sat in the House of Commons between 1710 and 1734. Grimston was born as William Luckyn, the younger son of Sir William Luckyn, 3rd Baronet, and his wife Mary Sherrington. In 1700 he succeeded to the estates, including Gorhambury near St Albans, of his great-uncle Sir Samuel Grimston, 3rd Baronet, of Bradfield, and assumed the surname of Grimston in lieu of Luckyn.