Duncan MacArthur may refer to:
Duncan MacArthur (Manitoba politician) (1840–1907), member of the Legislative Assembly of Manitoba Duncan MacArthur (Ontario politician) (1911–1914), member of the Legislative Assembly of Ontario
See also Duncan McArthur (1772–1839), military officer and politician from Ohio Duncan McArthur (Canadian politician) (1885 –1943), member of the Legislative Assembly of Ontario