Horst Janssen grew up with his mother and grandparents in Oldenburg; he never met his father. At the age of 14, his mother died of tuberculosis and Janssen moved to his aunt in Hamburg. Between 1946 and 1951 he studied at the State Art School in Hamburg, was a student of Alfred Mahlau and trained in free and applied graphics. In his early work of colored woodcuts, an expressionist formal language predominates, but a tendency towards the surreal and grotesque can already be seen in these works. From the 1950s onwards, Janssen established himself in Hamburg as a versatile graphic artist using a wide range of techniques; in addition to lithographs, he primarily created etchings. He is considered the most productive and important German illustrator of the post-war period. In 1997 the Horst Janssen Cabinet was set up in the Hamburger Kunsthalle and in 2000 the Horst Janssen Museum opened in his hometown of Oldenburg. His works are characterized by satirical, sarcastic and socially critical elements; they show a tendency towards New Objectivity and an early psychological realism based on the model of Edvard Munch and James Ensor.