Thomas Sinclair (politician, 1857–1940)

Thomas Sinclair, (17 December 1857 – 25 November 1940) was an Irish unionist politician.

Sinclair studied at Queen's University, Belfast before working as a surgeon. He was elected to the Senate of Northern Ireland on its creation in 1921.

He was elected as an Ulster Unionist Party Member of Parliament (MP) for Queen's University of Belfast at the 1923 United Kingdom general election. From 1935 to 1937, Sinclair served as Deputy Speaker of the Senate of Northern Ireland. He resigned his Westminster seat on 18 September 1940 by appointment as Steward of the Chiltern Hundreds. but held his Senate seat until his death in November.

The businessman and politician Thomas Sinclair was a relative of Sinclair.