| Ulster | |
| Source1 Coordinates: | 50.8422°N 9.9853°W |
| Mouth Coordinates: | 50.8433°N 9.9847°W |
| Subdivision Type1: | Country |
| Length: | 57.3km (35.6miles) |
| Basin Size: | 422km2 |
The Ulster is a 57adj=midNaNadj=mid river in Central Germany that flows through the states of Thuringia and Hesse.
The river originates in the Rhön Mountains, near the town of Ehrenberg. It then flows primarily in a northerly direction, through the towns of Hilders, Tann, Geisa, and Unterbreizbach. It flows from the left into the Werre River in Philippsthal.