John McLennan (1821-December 18, 1893) was an Ontario businessman and political figure. He represented Glengarry as a Liberal-Conservative member of the Canadian House of Commons from 1879 to 1882.
He was born in Williamstown in Upper Canada in 1821, the son of a Scottish immigrant. He served as president of the Montreal Board of Trade and vice-president of the Merchants' Bank of Canada. With his brother Hugh, he established a firm involved in shipping and grain processing. McLennan lived at Lancaster. He died in Montreal in 1893.