Sir John Joseph Caldwell Abbott, PC, KCMG, QC (March 12, 1821 – October 30, 1893) was a Canadian lawyer and politician, Freemason, who served as the third prime minister of Canada (and its first native-born one – both Macdonald and Mackenzie having been born in Scotland), in office from 1891 to 1892. He held office as the leader of the Conservative Party.

Abbott was born in what is now Saint-André-d'Argenteuil, Quebec. He studied law at McGill University and became one of Montreal's best-known lawyers, later returning to McGill as a professor of law and earning a Doctor of Civil Law degree. He was perhaps best known for his successful defence of the perpetrators of the St. Albans Raid. Abbott involved himself in politics from a young age, signing the Montreal Annexation Manifesto in 1849 – which he later regretted – and winning election to the Legislative Assembly of the Province of Canada in 1860. In the lead-up to Confederation he was a prominent advocate for the rights of English-speaking Quebecers.

In the 1867 federal election, Abbott was elected to the new House of Commons of Canada as a member of the Conservative Party. A telegram leaked from his office played a key part in the Pacific Scandal of 1873, which led to the downfall of John A. Macdonald's first government. Abbott was appointed to the Senate in 1887, in order to become Leader of the Government in the Senate. He became prime minister in June 1891 following Macdonald's death in office. Abbott was 70 years old at the time, and served only until November 1892 when he retired due to ill health. He died the following year.