Duncan Mackenzie (17 May 1861 – 25 August 1934) was a Scottish archaeologist who assisted Arthur Evans in his excavations of the Minoan palace at Knossos.

Appointed field supervisor of the excavation of Phylakopi by the British School at Athens, he worked closely with a team of professional archaeologists including Arthur Evans and David George Hogarth.

In her book on the Evans family (of which she was the latest member, being Arthur's half-sister), Time and Chance, Joan Evans gives this verbal portrait of MacKenzie in his prime: Mackenzie was a Scot with an inaudible Highland voice, a brush of red hair, an uncertain temper, a great command of languages, and great experience in keeping the records of an excavation.

MacKenzie kept the day book, or log of daily discoveries and served as a middle man between Evans and the inhabitants of Crete.

According to Evans, Mackenzie came to suffer from severe alcoholism and could not only no longer function as curator, but was fast declining into a demented state.

Whether the problem was alcoholism, denied for some reason by his family, or one of the brain disorders often inflicting the elderly, which Duncan then was, or some combination, Joan adds that he died in a state of "mental aberration.