| Fier | |
| Map: | Fier (rivière).png |
| Source1 Location: | Manigod |
| Source1 Coordinates: | 45.8125°N 6.4175°W |
| Mouth Location: | Rhône |
| Mouth Coordinates: | 45.9392°N 5.8319°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | France |
| Length: | 72.2km (44.9miles) |
| Source1 Elevation: | 1800m (5,900feet) |
| Mouth Elevation: | 255m (837feet) |
| Discharge1 Avg: | 41.2m3/s |
| Basin Size: | 1380km2 |
| Tributaries Left: | Thiou, Chéran |
The Fier (in French pronounced as /fjɛʁ/) is a 72.2km (44.9miles) long river in the Haute-Savoie and Savoie départements, southeastern France. Its source is at Manigod, in the Aravis Range. It flows generally west. It is a left tributary of the Rhône into which it flows at Seyssel.
Among its tributaries are the Chéran and the Thiou, that drains Lake Annecy.
This list is ordered from source to mouth: