Alexander Mackenzie commonly refers to:

Alexander Mackenzie (politician) (1822–1892), second Prime Minister of Canada
Sir Alexander Mackenzie (explorer) (1764–1820), explorer and commercial partner of the North West CompanyAlexander Mackenzie or MacKenzie may also refer to:

Alexander Mackenzie of Kintail (died after 1471), Scottish clan chief
Alexander Muir Mackenzie (1764–1835), Scottish advocate and landowner
Alexander Slidell Mackenzie (1803–1848), American naval officer involved in the "Somers Affair", and biographer
Alexander Mackenzie (historian) (1838–1898), Scottish historian
Alexander Slidell MacKenzie (1842–1867), officer in the US Navy during the American Civil War
Alexander Mackenzie (civil servant) (1842–1902), British colonial official in Burma
Alexander Mackenzie (engineer) (1844–1921), US Army Chief of Engineers
Sir Alexander Mackenzie (composer) (1847–1935), Scottish violinist, conductor, composer and head of the Royal Academy of Music in London
Alexander Marshall Mackenzie (1848–1933), Scottish architect
Alick Mackenzie (Alexander Cecil Knox Mackenzie, 1870–1947), Australian cricketer
Alexander George Robertson Mackenzie (1879–1963), Scottish architect; son of Alexander Marshall Mackenzie
Alex Mackenzie (1885–1965), Scottish character actor
Lex MacKenzie (Addison Alexander "A.A." MacKenzie, 1885–1970), Canadian politician
Alexander Mackenzie (artist) (1923–2002), St Ives school artist
Sandy Mackenzie (Alexander Mackenzie, born 1941), Australian politician
Gregor MacKenzie (Alexander David Gregor MacKenzie, born 1956), Scottish rugby player
Alexander MacKenzie (priest) (1876–1969), Provost of St Andrew's Cathedral, Inverness