| Official Name: | Alcosser |
| Other Name: | Alcocer de Planes |
| Type: | municipality |
| Mapsize: | 250px |
| Pushpin Map: | Spain Valencian Community |
| Pushpin Map Caption: | Location within the Valencian Community |
| Subdivision Type: | Country |
| Subdivision Name: | Spain |
| Subdivision Name1: | Alicante |
| Subdivision Name2: | Comtat |
| Area Total Km2: | 4.39 |
| Population Density Km2: | auto |
| Elevation M: | 350 |
| Population Blank1 Title: | Language |
| Population Blank1: | Valencian |
| Population Demonyms: | Alcosserí, Alcosserina (Catalan) |
| Coordinates: | 38.7944°N -0.4025°W |
| Blank Name: | Distance to Alicante: |
| Blank Info: | 80km (50miles) |
Alcosser (alkoˈseɾ/ or Alcocer de Planes pronounced as /es/) is a municipality in the Valencian comarca of Comtat, in the province of Alicante, Spain.
It is situated on the shore of the Serpis river, south of the Serra de Benicadell, in the central part of the Foia de Cocentaina. It is bordered on the north by Gaianes, on the east by Planes, on the west by Muro d'Alcoi, and on the south by Benimarfull.