| Mouth location | Schorgast |
|---|---|
| Mouth coordinates | 50.1078°N 11.6094°E |
| Progression | Schorgast→ |
| Country | Germany |
| State | Bavaria |
| Length | 14.0 km |
| Tributaries right | Kleiner Koserbach |
Koserbach (in its upper course: Großer Koserbach) (also: Koser) is a river of Bavaria, Germany. It is a right tributary of the Schorgast in Wirsberg.