Sir William Lowther, 1st Baronet (8 June 1663 – 6 March 1729) was an English landowner from Swillington, West Yorkshire, and a baronet in the Baronetage of Great Britain. He was the eldest son of Sir William Lowther by his wife, Catherine Harrison. He was educated in Yorkshire at Barwick-in-Elmet School, before being admitted to Christ's College, Cambridge, on 17 May 1681. Eighteen months later, on 14 December 1682, he was admitted to Gray's Inn, one of the professional bodies for English lawyers. and two daughters, Amabella and Jane, who both died unmarried.