Lillsjön is a small, former lake in Norra Djurgården, a semi-rural area in north-eastern central Stockholm, Sweden, forming part of the Royal National City Park. Today transformed into a wetland, it is often mentioned as one of the six lakes in the area, the other being: Laduviken, Uggleviken, Isbladskärret, Lappkärret, and Spegeldammen.