Thomas Thynne, 2nd Marquess of Bath KG (January 25, 1765 – March 27, 1837) was the son of Thomas Thynne, 1st Marquess of Bath. He was styled Viscount Weymouth from 1789 until acceding to the marquessate in 1796.

Thynne was educated at Winchester College and graduated from St John's College, Cambridge in 1787, with a Master of Arts (MA). Between 1786 and 1790, he was M.P. (Tory) for Weobley and for Bath from 1790 to 1796.

He married Hon. Isabella Elizabeth Byng, daughter of George Byng, 4th Viscount Torrington, on 14 April 1794. They had seven children:

• Thomas Thynne, Viscount Weymouth (1796–1837), married Harriet Robbins.
• Henry Frederick Thynne, 3rd Marquess of Bath (1797–1837)
• Reverend Lord John Thynne (1798–1881), married Anne Beresford and had issue.
• Lady Elizabeth Thynne (c. 1801–1866), married John Campbell, 1st Earl Cawdor and had issue.
• Lady Louisa Thynne (c. 1808–1859), married Henry Lascelles, 3rd Earl of Harewood and had issue.
• Lady Charlotte Anne Thynne (1811–1895), married Walter Montagu-Douglas-Scott, 5th Duke of Buccleuch and had issue.
• Reverend Lord Charles Thynne (1813–1894), Harriet Bagot and had issue.

He was Lord Lieutenant of Somerset between 1819 and 1837 and was invested as a Knight of the Garter on 16 July 1823.

Lord Bath died in 1837, aged 72 and was buried at his home, Longleat House.