John Maynard Sinclair (4 August 1896 – 31 January 1953) was a unionist politician in Northern Ireland. Born in Belfast, in 1896, son of John Sinclair DL and Alice Montgomery, he was educated at the Royal Belfast Academical Institution, and in Switzerland. He served in the British Army during World War I. He was a director of the Eagle Star Insurance Company and Chairman of Vulcanite Ltd.