Hartevatnet or Hartevatn is a lake in the municipality of Bykle in Agder county, Norway. It is located along the river Otra, on the south side of the village of Hovden. The lake is a good fishing spot and contains many brown trout. The Norwegian National Road 9 runs along the eastern shore of the lake. The lake Skyvatn lies about 6 kilometres (3.7 mi) to the northwest and the lake Holmavatnet lies about 13 kilometres (8.1 mi) to the northwest.

The lake is a man-made reservoir. It was formed by the building of a hydro-electric dam on the river Otra. It is also connected to the nearby lake Breivevatnet by a canal.

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