John Stewart McLennan (5 November 1853 – 15 September 1939) was a Conservative member of the Senate of Canada.

The son of Hugh McLennan and Isabella Stewart, he was educated at the High School of Montreal, McGill University, and Concordia, and moved to Sydney, Nova Scotia.

McLennan was married twice: to Louise Bradley in 1881 and to Grace Henoys Tytus in 1915.

McLennan was the author of Louisbourg, from its foundation to its fall, 1713-1758, [1] first published in 1918.

[1] He was appointed to the Senate on 10 February 1916 for the Sydney, Nova Scotia division following nomination by Prime Minister Robert Borden.