| Coordinates | 42°36′S 255°54′W / 42.6°S 255.9°W |
|---|---|
| Length | 945.0 |
| Naming | Word for "planet" in Gaelic |
Reull Vallis is a valley on Mars that appears to have been carved by water. It runs westward into Hellas Planitia. It is named after the Gaelic word for planet. It is found in the Hellas quadrangle.