Hans-Joachim Niemann (born 26 April 1941 in Kiel) is a German philosopher and PhD chemist,[1] who has become known especially as a translator and editor of works by Karl Popper, including first editions and first translations. As a scholarly writer, he first published scientific papers, then many essays and several books on Karl Popper's philosophy and Critical Rationalism, including a 400-page Lexicon of Critical Rationalism.[2] His Popper studies helped to establish Karl Popper as a major ethicist and as an important biophilosopher.