Knappensee (German) or Hórnikečanski jězor (Upper Sorbian) was a municipality in the northeastern part of Saxony, Germany, east of Hoyerswerda.
It was formed in 1995 by the merger of the three municipalities Groß Särchen, Koblenz and Wartha,[1] and was named after the lake Knappensee.
In 2004 it was disbanded. Groß Särchen and Koblenz became parts of Lohsa, Wartha became a part of Königswartha.[2]