Lyseren is a lake located in Spydeberg municipality in Østfold and Enebakk municipality in Akershus.
The lake is naturally inhabited by a ra. The outlet is Smalelva, which flows south and out in Glomma close to where the Østfoldbanen crosses the river.
Besides rich stocks of fish and ducks, there is the local water bat at Lyseren.
Lyseren is a drinking water source for large parts of Spydeberg. There is a lot of cabins around the lake.