The German drawer and graphic artist Horst Janssen is born outside marriage on November 14, 1929 in Hamburg. He spends his childhood in Oldenburg with his grandfather who adopts him. After his grandfather's death in 1939 and the death of his mother in 1941, Janssen is raised in the National Political Institute of Education in Haselünne in the Emsland.
Horst Janssen returns to Hamburg in 1945 and studies at the State School of Art from 1946 to 1951 under Alfred Mahlau. By aid of his teacher, Janssen finds employment at the colored fancy paper factory of Guido Dessauer in Aschaffenburg from 1952 to 1956. Besides portraits in oil, Janssen makes ceramic objects, but he most of all learns the art of lithographs in the factory's lithographic workshop. Janssen makes large format woodcuts in colors in 1957/58, in a partly expressionist, partly surreal scurrility. These works make for Janssen's first success as an artist and grant him a regular income, as he is meanwhile married and has a child.
Horst Janssen is taught the technique of etching by Paul Wunderlich, which he will soon master, making it his preferred technique. His etchings show a great love for the detail and depict erotic fantasies. As of 1963 Janssen more and more uses the direct medium of drawing, as it is a means of expressing his subtle and striking ideas. Additionally, the artists reflects on himself in numerous self-portraits.
Horst Janssen's graphic oeuvre comprises some 4.000 sheets and 47 series of etchings.
Horst Janssen dies in Hamburg in 1995. The Hamburg Kunsthalle sets up a Janssen cabinet in 1997, exhibiting the graphic sheets from the collection of Janssen's printer Hartmut Frielingshaus. The Janssen museum is opened in Oldenburg in 2000.