John Garth (1701–1764) was a British politician.
He was the son of Colonel Thomas Garth and Elizabeth Colleton, granddaughter of Sir John Colleton, 1st Baronet, one of the original proprietors of South Carolina. John Garth was also a nephew of Sir Samuel Garth the physician. His family home in Devizes was Brownston House,  a large Grade 1 listed house on New Park Street.
He became the Recorder for Devizes in 1732, a role roughly equivalent to the Town Clerk today and usually held by a lawyer. He was elected Member of Parliament (MP) for Devizes in 1740 and was twice re-elected to the seat before his death in 1764.
Garth died in 1764 and was buried in St Mary’s Churchyard, Devizes on 2 January 1765. He had married Rebecca Brompton, granddaughter of Sir Richard Raynsford, English judge and Chief Justice of the King's Bench. Rebecca (1713–1785) and their daughter Elizabeth (1739–1790) were also buried in St Mary’s. His daughter Frances was baptised in St.Mary’s Church in January 1744 and buried there in 1768. His son Thomas was baptised there in September 1745; he was to become an Army general and Equerry to George III. One monument of St. Mary’s commemorates John Garth himself and in the chancel there are monuments to the memory of his widow and children.
His sons included:
- General Thomas Garth (1744–1829) Royal Equerry
- General George Garth (abt 1733–1819) British General in American Revolutionary War, Colonel of the 17th Regiment of Foot
- Charles Garth MP, (1734–1784) Government Agent for South Carolina, Georgia and Maryland. He succeeded his father as MP for Devizes, and was also Recorder of Devizes.
- The Annual Register, Edmund Burke, 1830
- Blackwoods Edinburgh Magazine, 1819, page 506
|Parliament of the United Kingdom|
and Sir Joseph Eyles
|Member of Parliament for Devizes
With: Francis Eyles (1740–1742)
George Lee (1742–1747)
William Willy (1747–1764)
and William Willy