Thomas Thynne, 1st Marquess of Bath (13 September 1734 – 19 November 1796), of Longleat in Wiltshire, was a British politician who held office under King George III.

Sir John owed his wealth and position to the favour of his master, the Lord Protector Edward Seymour, 1st Duke of Somerset.

Another famous ancestor was Thomas Thynne (1648–1682), called on account of his wealth "Tom of Ten Thousand" and celebrated by Dryden as Issachar in Absalom and Achitophel, who was murdered in London in February 1682.

[1] He succeeded his father as 3rd Viscount Weymouth in January 1751 and served as Lord Lieutenant of Ireland for a short time during 1765, although he never visited that country.

[3] Having become prominent in British politics, he was appointed Secretary of State for the Northern Department in January 1768 and acted with great promptitude during the unrest caused by John Wilkes and the Middlesex election of 1768.