Sir John Sparrow David Thompson, PC KCMG QC (November 10, 1845 – December 12, 1894) was a Canadian lawyer, judge, politician, and university professor, who served as the fourth Prime Minister of Canada from December 5, 1892 until his sudden death in office on December 12, 1894. He also served as the fifth Premier of Nova Scotia in 1882. He was the first Roman Catholic to hold the office of Prime Minister.