| Langsjøen | |
| Pushpin Map: | Innlandet#Norway |
| Pushpin Label Position: | bottom |
| Pushpin Map Caption: | Location of the lake |
| Coordinates: | 62.1636°N 11.5942°W |
| Location: | Tolga, Engerdal (Innlandet) |
| Inflow: | Hola river |
| Outflow: | Sømåa river |
| Basin Countries: | Norway |
| Area: | 6.35km2 |
| Reference: | NVE |
Langsjøen is a lake in the municipalities of Tolga and Engerdal in Innlandet county, Norway. The 6.35km2 lake lies in the Sømådalen valley in the southeastern part of the municipality, just west of the large lake Femund. The village of Øversjødalen lies at the north end of the lake and the mountain Elgspiggen lies about west of the lake.[1]