Demetrius III may refer to:
- Demetrius III of Abkhazia (fl. 969–976), King of Abkhazia
- Demetrius III Aniketos (fl. 100 BC), Indo-Greek king
- Demetrius III Eucaerus (died 88 BC), Seleucid king
- Demetrius III of Georgia (c. 1413–1453), King of Georgia
Demetrius III may refer to: