| Koserbach | |
| Mouth Coordinates: | 50.1078°N 11.6094°W |
| Progression: | Schorgast→ |
| Subdivision Type1: | Country |
| Length: | 14km (09miles) |
| 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.