Topsæ is a lake in the municipality of Bygland in Agder county, Norway. The 2.4-square-kilometre (0.93 sq mi) lake is located 3 kilometres (1.9 mi) east of the lake Hovatn, about 10 kilometres (6.2 mi) northeast of the village of Åraksbø. The Topsæfossen waterfall is located at the north end of the lake at the primary inflow. At the southeastern corner of the lake, there is a small dam to regulate the outflow of the lake into the Tovdalselva watershed.

• List of lakes in Aust-Agder
• List of lakes in Norway