The Bloody Wednesday of Olkusz or Bloody Wednesday in Olkusz (Polish: Krwawa środa w Olkuszu) was perpetrated by the German occupiers in Olkusz on July 31, 1940, during World War II, in which a number of Polish civilians were murdered.
The incident began with the retaliation for the death of a German policeman killed by a burglar on July 14. Two days later, in a reprisal act of collective punishment, 20 civilian hostages, ethnic Poles from Olkusz and its surrounding region, were shot in the Olkusz neighborhood of Parcze. Two weeks later, on a day that became known as the "Bloody Wednesday of Olkusz", a second German punitive expedition chased all the men from Olkusz, both ethnic Poles as well as Polish Jews, to the market square and city squares, where they were brutally tortured and harassed for several hours, with many wounded and three fatalities. One of those three was identified as a Polish-American Jew, the other two being a Polish electrician and a local priest.
Until the early 21st century, a number of high-profile works published outside Poland summarizing this incident have incorrectly identified the victims as only "Polish Jews" or just "Jews", despite the fact that the majority of the fatalities were gentile Poles.