Alexander Marshall MacKenzie (1 January 1848 – 4 May 1933) was a Scottish architect responsible for prestigious projects including the headquarters of the Isle of Man Banking Company in Douglas, and Australia House and the Waldorf Hotel in London.
He received royal patronage with the design of Crathie Kirk (1893) and was subsequently chosen by the Duke and Duchess of Fife (the Prince of Wales's daughter Princess Louise) for the new (3rd) Mar Lodge (1895).
Born in Elgin in Morayshire, on 1 January 1848, the son of Thomas Mackenzie, architect and his wife Helen Margaret McInnes. He was educated at Aberdeen University and trained with James Matthews (1820–98) in Aberdeen from 1863 to 1868. He began his career in the office of David Bryce in Edinburgh.
In 1877 he went into partnership in Aberdeen with James Matthews, and later with his own son. The majority of his work was undertaken in northern Scotland. In Aberdeen his work includes St Mark's Church on Rosemount Viaduct (1892).
Elphinstone Hall (1926) at King's College, the Art Gallery (1885), frontage of Marischal College (1904–6) and Greyfriars Church (1906), Harbour Offices (Regent Quay) and Langstane Kirk (or West Church of St Andrew).
During 1895 Marshall Mackenzie undertook extensive internal restoration work at Udny Parish Church. The buildings structure, which was designed by John Smith in 1821, was not altered but the roof was replaced.