The Generalplan Ost, abbreviated GPO, was Nazi Germany's blueprint for the genocide, extermination and large-scale ethnic cleansing of Slavs, Eastern European Jews, and other indigenous peoples of Eastern Europe categorized as "Untermensch" in Nazi ideology. The campaign was a precursor to Nazi Germany's planned colonisation of Central and Eastern Europe by Germanic settlers, and it was carried out through systematic massacres, mass starvations, chattel labour, mass-rapes, child abductions, and sexual slavery.

The Slavs or Slavic people are a group of peoples who speak Slavic languages. Slavs are geographically distributed throughout the northern parts of Eurasia; they predominantly inhabit Central Europe, Eastern Europe, and Southeastern Europe, though there is a large Slavic minority scattered across the Baltic states, Northern Asia, and Central Asia, and a substantial Slavic diaspora in the Americas, Western Europe, and Northern Europe.