Rafał Lemkin, primarily known within academic circles and among the foremost experts of international law, deserves to be ranked among key figures of the 20th century as a prominent intellectual, researcher of totalitarian crimes and author of the concept of genocide. In addition to Jan Nowak-Jeziorański, Jan Karski, Witold Pilecki and Szmul Zygielbojm, he was one of those who tried to make the world aware of the tragedy that took place in Europe under the occupation of two totalitarian regimes. His concept gained widespread recognition and forever changed international law and the way of thinking about the desired shape of relations between human communities.