Thomas Underwood (May 6, 1863 – May 10, 1948) was a building developer and the 13th mayor of Calgary, Alberta. Born in Asfordby, Leicestershire, England in 1863, Underwood emigrated to Canada when he was 20. A carpenter by trade, he arrived in Winnipeg, Manitoba in 1883. At first, he worked as a farm hand. Two years later, he joined a Canadian Pacific Railway construction gang and was working in Craigellachie, British Columbia at the time of the last spike was driven to complete the transcontinental railroad. After the railroad was completed, he settled in Calgary.