Professor Ludwik Dobrzyński, an eminent scientist and popularizer of science, passed away on January 11, 2022, in his home in Warsaw, Poland, just before his 81st birthday. He was a specialist in solid-state physics. Later in his career, Ludwik also became interested in the effects of small doses of ionizing radiation on health. Professor Dobrzyński was one of the most outstanding physicists at the Polish Institute of Nuclear Research (IBJ), later transformed into the National Centre for Nuclear Research (NCBJ) at Świerk near Warsaw. He was also a well-recognized personality among the international low-dose radiation research community.