John Hampden-Trevor, 3rd Viscount Hampden PC (24 February 1748 – 9 September 1824), was a British diplomat.
He was the younger son of Robert Hampden, 1st Viscount Hampden and was educated at Westminster School and Christ Church, Oxford.
On 8 May 1773, he married Harriet Burton (1751–1829), daughter of the Rev.
He succeeded to the Viscountcy of Hampden on 20 August 1824, just three weeks before his death.
This biography of a viscount or viscountess in the Peerage of Great Britain is a stub.