Rotzberg or Rotzburg is a ruined castle in the municipality of Ennetmoos in the canton of Nidwalden in Switzerland .

Nothing is known about the original name, construction date or owner of the castle. Prehistoric pottery shards have been discovered under the castle, as well as medieval artifacts from the 10th to 12th centuries. In 1150 the Freiherr von Rotenburg granted extensive lands around Stans and Ennetmoos to Murbach-Lucerne Monastery. It is possible that he may have built a castle on these lands to administer his lands. In an 1197 record the Rozziberg is listed as owing taxes to Engelberg Abbey , from which castles were normally exempt.