Sir John Sparrow David Thompson PC KCMG QC (November 10, 1845 – December 12, 1894) was a Canadian lawyer, judge, and politician who served as the fourth prime minister of Canada, in office from 1892 until his death. He had previously been premier of Nova Scotia for a brief period in 1882.

Thompson was born in Halifax, Nova Scotia. He trained as a lawyer and was called to the bar in 1865. Thompson was elected to the Nova Scotia House of Assembly in 1877 as a representative of the Conservative Party. He became the provincial attorney general the following year, in Simon Holmes' government, replaced Holmes as premier in 1882. However, he served for only two months before losing the 1882 general election to the Liberal Party. After losing the premiership, he accepted an appointment to the Nova Scotia Supreme Court.

In 1885, Thompson entered federal politics at the personal request of Sir John A. Macdonald, becoming Minister of Justice. In that role he was the driving force behind the enactment of the Canadian Criminal Code. Thompson became prime minister in 1892, following the retirement of John Abbott. He was the first Roman Catholic to hold the position. On a trip to England in 1894, Thompson unexpectedly suffered a heart attack and died, aged 49. He is the second and most recent Canadian prime minister to have died in office, after Sir John A. Macdonald.