| Demenika | |
| Name Local: | Δεμένικα |
| Coordinates: | 38.2°N 66°W |
| Elevation: | 45 |
| Georegion: | Peloponnese |
| Periph: | West Greece |
| Periphunit: | Achaea |
| Municipality: | Patras |
| Municunit: | Messatida |
| Community: | Saravali |
| Population As Of: | 2021 |
| Population: | 2845 |
| Postal Code: | 265 00 |
| Area Code: | 2610 |
| Licence: | AX |
Demenika (el|Δεμένικα) is a village/suburb in the municipality of Patras, Achaea, Greece. It lies 5km (03miles) south of the city centre, south of the river Glafkos. It is part of the community of Saravali within the municipal unit of Messatida. It is 2 km northeast of Ovrya and 4 km east of Paralia. The Greek National Road 33 (Patras - Tripoli) passes through the village, and the new Greek National Road 9 (Patras - Pyrgos) passes south of the village.