Sir Thomas Kay Stuart Sidey (1908 - 28 October 2007) was the Mayor of Dunedin, New Zealand from 1959 to 1965 for the Citizens party, and was on the Dunedin City Council from 1947 to 1983. He stood for Parliament three times.
He was a Dunedin lawyer, educated at Otago Boys' High School and the University of Otago. He was on the Otago University Council for 34 years. In World War II he was a Major in the New Zealand Army in the Pacific. He ran the Wickliffe Press in Dunedin and bred racehorses.
He was brought up in Corstophine House. He was the only child of Sir Thomas Sidey, a Dunedin Member of Parliament, Cabinet Minister and lawyer. He married Beryl Thomas in 1933; they had 1 son and 1 daughter.