Alexander Duff

Alexander Duff may refer to:


 * Alexander Duff, 3rd Earl Fife (1731–1811), Scottish nobleman
 * Sir Alexander Duff (British Army officer) (1777–1851), Scottish general and Lord-Lieutenant of Moray
 * Alexander Duff (missionary) (1806–1878), Scottish missionary
 * Alexander Duff, 1st Duke of Fife (1849–1912), Scottish nobleman and son-in-law of King Edward VII
 * Sir Alexander Duff (Royal Navy officer) (1862–1933), British admiral