Steinn Olafur Thompson (November 23, 1893 – August 19, 1972) was a politician in Manitoba, Canada. He served in the Legislative Assembly of Manitoba as a Liberal-Progressive from 1945 to 1958.
Thompson was born in Winnipeg and grew up in Selkirk. He was educated at Wesley College and the Manitoba Medical College. He practised as a doctor in Riverton, Manitoba after serving overseas with the Canadian Army in World War I.
He died at home in Riverton at the age of 78.
Thompson's eulogy was delivered by Philip Petursson, a Unitarian minister who served in the Manitoba assembly as a New Democrat.