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).