John Thurso, Scottish businessman and politician
John Archibald Sinclair, 3rd Viscount Thurso (born 10 September 1953), known also as John Thurso, is a Scottish businessman, Liberal Democrat politician and hereditary peer who is notable for having served in the House of Lords both before and after a period in the House of Commons.

Born to the Sinclair family, Thurso was educated at Eton College before entering management roles in the tourism and hospitality industry. He first joined parliament in the House of Lords as a hereditary peer in 1995 and served until 1999, when he was among the majority of hereditary peers who were removed from parliament following the House of Lords Act 1999.

Thurso was elected Member of Parliament (MP) for Caithness, Sutherland and Easter Ross at the 2001 general election, becoming the fifth generation of the Sinclair family to represent the Caithness area in the House of Commons. He held the seat until he was defeated at the 2015 general election by the Scottish National Party candidate, Paul Monaghan. During his time serving in the Commons, Thurso was chair of the Finance and Services Committee from 2010 to 2015. In 2016, Thurso returned to the House of Lords after winning a by-election to fill a vacancy among the remaining Liberal Democrat hereditary peers. He became chair of VisitScotland in 2016 and later became Lord Lieutenant of Caithness in 2017.