James Alexander Stewart-Mackenzie (23 September 1784 – 24 September 1843), was a Scottish politician and British colonial administrator.
Born James Alexander Stewart, the son of Vice Admiral Keith Stewart (who died when James was eleven), he assumed the surname Stewart-Mackenzie after his marriage on 21 May 1817 to Mary Elizabeth Frederica Mackenzie ("the Hooded Lassie"), daughter of Francis Mackenzie, 1st Baron Seaforth.
Stewart-Mackenzie was elected to the House of Commons as Member of Parliament for Ross-shire in 1831. When that constituency was abolished in 1832, he was elected for the new Ross and Cromarty, serving until 1837.
He left the House of Commons to become Governor of Ceylon from March 1837 to 1840, and then Lord High Commissioner of the Ionian Islands (based in Corfu) from December 1840 to 1843.
He sold the house and grounds of Woodfall Gardens, Glasserton in 1819 to Stair Hathorn-Stewart at the neighbouring Physgill estate.
His great-grandson, James Alexander Francis Humberston Mackenzie, was created Baron Seaforth in 1921.