Walter Cunningham Thomson (December 21, 1895 – April 27, 1964) was a politician, lawyer and rancher in Ontario, Canada. Thomson first ran for the leadership of the Ontario Liberal Party in 1943 but came in fourth place losing to Harry Nixon. He was first elected to the Canadian House of Commons in the 1949 federal election.In 1950, he left federal politics and ran again for the leadership of the Ontario Liberal Party and won, defeating social reformer Harry Cassidy.