Thompson, Sir John Sparrow David, 1844–94, Canadian political leader, b. Nova Scotia. He was elected (1877) to the provincial assembly, was briefly provincial prime minister, and then was made a justice of the supreme court of Nova Scotia. In 1885, Sir John Macdonald appointed him minister of justice for Canada. In that post Thompson skillfully defended the government's position in the debates on the execution (1885) of Louis Riel and on the Jesuit Estates Act (1888). In 1892 he became prime minister of Canada. He died suddenly in England, shortly after having been sworn in as privy councilor. He was knighted in 1888.