Edward James Lennox (September 12, 1854 – April 15, 1933) was a Toronto-based architect who designed several of the city's most notable landmarks in the late nineteenth and early twentieth centuries, including Old City Hall and Casa Loma.

The son of Irish immigrants, he studied at the Mechanics' Institute in Toronto, where he finished first in his class.

He rose to the top of his profession when he won the contract for Toronto City Hall in 1886.

His creative prowess in the Romanesque Revival style was especially important in The Annex neighbourhood, where Lennox designed the Lewis Lukes House at 37 Madison Avenue in the mid-1880s, pioneering the Annex House.

Co-Founder of Lennox Architects Limited Huntsville Ontario with Susana Marques.