John Angus MacMillan (27 March 1889 – 12 August 1956) was a Liberal party member of the House of Commons of Canada. He was born in Nova Scotia and became a barrister. MacMillan attended Dalhousie University. He became mayor of Wadena, Saskatchewan in 1917 and that same year was elected a Liberal member of the Legislative Assembly of Saskatchewan for the Wadena provincial riding. He served in that legislature until his defeat in the 1921 provincial election.