Robert Stirton Thornton

Robert Stirton Thornton (May 8, 1863 – 17 September 1936) was a politician in Manitoba, Canada. He served in the Legislative Assembly of Manitoba from 1907 to 1910, and again from 1914 to 1922. Thornton was a Liberal, and served as a cabinet minister in the government or Tobias Norris.

Thornton was born in Edinburgh, Scotland. He was educated at Heriots School and the University of Edinburgh, receiving medical certification from the latter institution in 1884. He moved to Canada in 1884, and received an LL.D. from Queen's University in Kingston, Ontario. Thornton worked as a physician, serving as president of the Manitoba Medical Council (1896) and the Medical Council of Canada. He was also a horticulturalist and an active freemason, serving as Grand Master from 1900 of 1902.

He was first elected to the Manitoba legislature in the 1907 provincial election, defeating Conservative incumbent Edward Briggs by 41 votes in the constituency of Deloraine. Premier Rodmond Roblin's Conservatives won the election, and Thornton served as an opposition member for the next three years. He lost to Conservative John C.W. Reid by six votes in the 1910 campaign.