Viscount Weymouth

Marquessate of Bath
Quarterly: 1st and 4th, barry of ten Or and Sable (Botteville); 2nd and 3rd, Argent, a lion rampant with tail nowed and erected Gules (Thynne).
Creation date	18 August 1789
Monarch	King George III
Peerage	Peerage of Great Britain
First holder	Thomas, Marquess of Bath
Present holder	Alexander, Marquess of Bath
Heir apparent	Ceawlin, Viscount Weymouth
Remainder to	heirs male of the body lawfully begotten
Subsidiary titles	Viscount Weymouth Baron Thynne Baronet (of Caus Castle)
Seat(s)	Longleat

Marquess of Bath is a title in the Peerage of Great Britain. It was created in 1789 for Thomas Thynne, Viscount Weymouth. The Marquess holds the subsidiary titles Baron Thynne, of Warminster in the County of Wiltshire , and Viscount Weymouth, both created in 1682 in the Peerage of England. He is also a baronet in the Baronetage of England.

The Thynne family descends from the soldier and courtier Sir John Thynne (died 1580), who constructed Longleat House between 1567 and 1579. In 1641 his great-grandson Henry Frederick Thynne was created a Baronet, of Caus Castle, in the Baronetage of England (some sources claim that the territorial designation is "Kempsford in the County of Gloucester"). He was succeeded by his son, the second Baronet. He represented Oxford University and Tamworth in the House of Commons and also served as Envoy to Sweden. In 1682 he was raised to the Peerage of England as Baron Thynne, of Warminster in the County of Wilts, and Viscount Weymouth, in the County of Dorset, with remainder to his younger brothers James Thynne (who died unmarried) and Henry Frederick Thynne and the heirs male of their bodies.

Lord Weymouth died without surviving male issue in 1714 (one of his three sons, the Honourable Henry Thynne, represented Weymouth and Melcombe Regis and Tamworth in Parliament but had died in 1708, leaving only daughters) and was succeeded in the peerages (according to the special remainders) by his great-nephew, the second Viscount. He was the grandson of the aforementioned Henry Frederick Thynne, brother of the first Viscount. He married as his second wife Lady Louisa Carteret, daughter of John, Earl Granville, a female-line grandson of John, Earl of Bath (a title which had become extinct in 1711). Lord Weymouth was succeeded by his eldest son, the third Viscount. He was a prominent statesman and served as Secretary of State for the Northern Department and as Secretary of State for the Southern Department. In 1789 the Bath title held by his ancestors was revived when he was created Marquess of Bath.