John Thynne, 3rd Baron Carteret

John Thynne, 3rd Baron Carteret, was born on 28 December 1772 and died on 10 March 1849. He was a British peer and politician who held the title of Baron Carteret from 1838 until his death.

He was the third son of Thomas Thynne, 1st Marquess of Bath, and Lady Elizabeth Bentinck, who was the daughter of William Bentinck, 2nd Duke of Portland. His familial lineage connected him to prominent British aristocratic families.

Thynne received his education at St John's College, Cambridge.

His political career began when he was elected to Parliament for Weobly in May 1796; however, his initial tenure lasted only until December of the same year. Subsequently, he represented Bath in Parliament from 1796 to 1832. During his time in Parliament, he served as Vice-Chamberlain of the Household from 1804 to 1812. In the same year, he was sworn into the Privy Council.

In 1838, upon the death of his elder brother, George Thynne, who died childless, he succeeded to the barony of Carteret and took his seat in the House of Lords.

In his personal life, Thynne married Mary Anne Master in 1801. She was the daughter of Thomas Master. The marriage produced no children. Following his death, Lady Carteret moved to Upper Brook Street in Mayfair.

John Thynne died at his residence, Hawnes Park, in March 1849, at the age of 76. With his death, the barony of Carteret became extinct due to the lack of heirs. The estate, however, was inherited by his nephew, the Reverend Lord John Thynne, who was the third son of Thomas Thynne, 2nd Marquess of Bath, and held the position of sub-Dean of Westminster.