Donald McMillan or MacMillan may refer to:

• Donald McMillan (Ontario politician) (1835–1914), Senator from Ontario
• Donald McMillan (Quebec politician) (1807–1876), who represented Vaudreuil in the 1st Canadian Parliament
• Donald Baxter MacMillan (1874–1970), American explorer
• Donald MacMillan (rugby union) (born 1930), rugby union player who represented Australia
• Don MacMillan (1928-2004), Australian Olympic athlete

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