Nedre Roasten is a lake in Femundsmarka National Park on the border of Innlandet and Trøndelag counties in Norway. The 2.29-square-kilometre (0.88 sq mi) lake sits on the border of the municipalities of Engerdal in Innlandet county and Røros in Trøndelag county. Nedre Roasten is about 50 kilometres (31 mi) southeast of the town of Røros and just under 9 kilometres (5.6 mi) from the border with Sweden. The lake lies about 5 kilometres (3.1 mi) east of the lake Femunden and about 8 kilometres (5.0 mi) west of the lake Rogen which sits along the Swedish border.

• List of lakes in Norway