Alexander Duncan
Alexander Duncan may refer to:
- Alexander Duncan (army officer), East India Company officer
- Alexander Duncan (athlete), British Olympic runner
- Alexander Duncan (bishop), Scottish Episcopal clergyman and bishop
- Alexander Duncan (politician), U.S. Representative from Ohio
- Alexander Duncan (police officer), Scottish police officer and Chief Commissioner of Victoria Police, 1937–1954
- Alex Duncan, former Australian rules footballer
- Alexander Duncan (doctor), British doctor who spent six years in a village high up in the Wakhan Corridor of north-eastern Afghanistan
- Alexander William Duncan, Scottish cricketer and rugby player
- Alexander Duncan (footballer), Scottish footballer