| Conflict: | Battle of Thessalonica |
| Date: | summer or autumn 380 AD |
| Place: | near Thessalonica, Macedonia |
| Result: | Gothic victory |
| Combatant1: | Eastern Roman Empire |
| Combatant2: | Goths |
| Commander1: | Theodosius I |
| Commander2: | Fritigern |
The Battle of Thessalonica was fought in the summer or autumn of 380 by Fritigern's Goths and a Roman army led by Theodosius I. Reconstituted after Adrianople, the East Roman army suffered another major defeat. Theodosius retreated to Thessalonica and surrendered control of operations to the Western Emperor, Gratian.