Wolfgang Justin Mommsen was a German historian best known for his influential work on Max Weber and his studies of modern German and British history. Educated in Marburg, Cologne, and Leeds, he taught at the University of Cologne before holding a professorship at the University of Düsseldorf, where he remained for nearly three decades, and also directed the German Historical Institute in London. His early biography of Weber and subsequent dissertation challenged prevailing interpretations, situating Weber as a liberal nationalist and imperialist and reshaping understanding of his political thought. Mommsen was a central figure in editing the Max Weber-Gesamtausgabe, the comprehensive edition of Weber’s works. His scholarship explored the “Sonderweg” thesis, arguing that Germany’s incomplete modernization and the persistence of authoritarian elites shaped the country’s trajectory toward the First World War and the rise of Nazism. Widely respected for his comparative perspective, he was also active in the Historikerstreit, affirming the Holocaust’s singularity.