The 'Battle of Haglebu' was a skirmish between a German-led small force, which included a number of collaborators, and a small Norwegian resistance force toward the end of the German occupation of Norway (26 April 1945).

A patrol of German and Norwegian police troops had been tipped off that weapons were hidden in Haglebu and arrived from Eggedal on a search. On the southern shore of Haglebuvannet, the German force divided to search both sides of the lake. On the western side, the Germans came under machine gun fire from men of the Milorg Norwegian military resistance movement, and soon came under attack on the eastern side as well. After about four hours, during which the Norwegians repulsed the German assaults, the Milorg groups carried out an orderly withdrawal before German reinforcements arrived.

Albeit a small battle and local in nature, it had a significant effect on the course of the war in Norway. The battle marked a defeat for Norwegians who were collaborating with the Germans. This may have contributed to the collaborators' acceptance of the German surrender, which prevented further fighting between Milorg and the collaborators.