| Gelug | |
| Name Other: | Lupac |
| Pushpin Map: | Romania |
| Subdivision Type1: | Country |
| Subdivision Name1: | Romania |
| Subdivision Type2: | Counties |
| Subdivision Name2: | Caraș-Severin County |
| Subdivision Type3: | Villages |
| Subdivision Name3: | Lupac |
| Length: | 18km (11miles) |
| Mouth: | Caraș |
| Mouth Coordinates: | 45.197°N 21.7923°W |
| Basin Size: | 95km2 |
| Tributaries Left: | Lupacul Mic, Stircovăț, Clocotici, Țerova, Nermed |
| Tributaries Right: | Țiganca, Rafnic, Jupalnic |
The Gelug (also: Lupac) is a right tributary of the river Caraș (Karaš) in Romania. It discharges into the Caraș near Goruia. Its length is 18km (11miles) and its basin size is 95km2.