(b Euskirchen, April 22, 1924; d Cologne, April 5, 1987).
German collector and restorer. After World War II he trained as a restorer of paintings in Cologne, Munich and Vienna. He worked in the Wallraf-Richartz-Museum in Cologne from 1949 and took charge of the restoration department in 1963. He started his collection with paintings by Cologne painters such as Peter Abelen (1884–1962), Joseph Fassbender, Peter Herkenrath (1900–93) and Ludwig Egidius Ronig (1885–1959). Under the stimulus of avant-garde exhibitions in Cologne and Düsseldorf, a keen interest in current events in the world of art and his friendships with artists and gallery owners, Hahn widened the scope of his collection. His advice as a connoisseur of contemporary art was valued not only by his museum colleagues but also by collectors such as Peter Ludwig.
Hahn assembled a remarkably complete collection of works by many artists closely connected with Nouveau Réalisme, including Arman, Christo, César, Jean Tinguely, ...