| Type: | parish |
| Official Name: | Serra d'El-Rei |
| Image Location: | Concelhopeniche-050605-freg-serra.jpg |
| Region: | Oeste e Vale do Tejo |
| Cim: | Oeste |
| District: | Leiria |
| Municipality: | Peniche |
| Coordinates: | 39.331°N -9.27°W |
| Area Total: | 8.92 |
| Population As Of: | 2011 |
| Population Total: | 1401 |
Serra d'El-Rei ('Mountains of the King') is a Portuguese parish in the municipality of Peniche on the Atlantic Coast. The population in 2011 was 1,401,[1] in an area of 8.92 km².[2] Serra d'El-Rei became a town on July 1, 2003.
It was at Serra d'El-Rei that King Peter I of Portugal lived with his lover Inês de Castro. His 14th-century castle in the town is now divided into three private living houses today.
Serra d'El-Rei is 7km (04miles) west of the historic walled-town of Óbidos, and 10 km east from Peniche.