Thomas Thynne, 1st Viscount Weymouth (1734–1796), was a British politician and nobleman. He was born into the prominent Thynne family and became known for his role in the House of Commons before being elevated to the peerage as Viscount Weymouth in 1789. His political career included serving as a Member of Parliament for Wiltshire and holding various governmental positions. As a landowner, Thynne was associated with the Longleat House, a grand estate in Wiltshire that remains a significant historical site. He was also involved in local affairs and contributed to the development of his estate and the surrounding area during his lifetime.