The Gudovac massacre was the mass killing of around 190 Bjelovar Serbs by the Croatian nationalist Ustaše movement on 28 April 1941, during World War II. The massacre occurred shortly after the German-led Axis invasion of Yugoslavia and the establishment of the Ustaše-led Axis puppet state known as the Independent State of Croatia (NDH). It was the first act of mass murder committed by the Ustaše upon coming to power, and presaged a wider Ustaše-perpetrated campaign of genocide against Serbs in the NDH that lasted until the end of the war.