Thomas Thynne, 2nd Marquess of Bath KG (25 January 1765 – 27 March 1837), styled Viscount Weymouth from 1789 until 1796, was a British peer.
Thynne was the eldest son of Thomas Thynne, 1st Marquess of Bath, who he succeeded as 2nd Marquess in 1796.
He was educated at Winchester College and admitted as a nobleman to St John's College, Cambridge in 1785, graduating M.A. in 1787.
Between 1786 and 1790, he was MP (Tory) for Weobley. He later sat for Bath from 1790 to 1796. 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 married the Honourable Isabella Elizabeth Byng, daughter of George Byng, 4th Viscount Torrington, on 14 April 1794. They had eleven children:
Lord Bath died in 1837, aged 72, and was buried at his home, Longleat House. His eldest son Thomas predeceased him by some two months and he was therefore succeeded by his second son Henry.