| Constantine Doukas | |
|---|---|
| Sebastokrator | |
| Ruler of Thessaly or Great Vlachia | |
| Reign | c. 1289–1303 |
| Predecessor | John I Doukas |
| Successor | John II Doukas |
| Died | 1303 |
| Issue | John II Doukas |
| Dynasty | Komnenodoukai |
| Father | John I Doukas |
| Mother | Hypomone |
Constantine Doukas (Greek: Κωνσταντίνος Δούκας, romanized: Kōnstantinos Doukas), Latinized as Ducas, was ruler of Thessaly from c. 1289 to his death in 1303.