Szmalcownik is a Polish term for blackmailers who exploited Jews in hiding and those aiding them during the Holocaust in occupied Poland, extracting money and valuables before often turning victims in for German bounties. Originating from German criminal jargon, the practice was widespread in Warsaw with an estimated 3,000–4,000 blackmailers, prompting Żegota and the Home Army to execute dozens by war's end. The phenomenon occurred throughout occupied Europe but was particularly documented in Poland.