Alexander Marshall Mackenzie was an architect active in the late-19th and early-20th centuries.
He was in practice with James Matthews (1820-98) in Aberdeen from 1877. From 1903, his son, Alexander George Robertson Mackenzie (1879-1963) joined the practice.
Mackenzie designed a number of public buildings in Aberdeen and London. In London, he and his son together designed the Waldorf Astoria Hotel (1906-7) and Australia House (1913-18), both in Aldwych.