Mack (b. 1931 Hesse, Germany) studied painting between 1950 and 1953 at the Staatliche Kunstakademie in Düsseldorf and in 1956 studied philosophy at the University of Cologne. In 1957 he founded the ZERO group together with Otto Piene and with him (and later Uecker) organised the legendary evening exhibitions in the studio in Gladbacher Strasse in Düsseldorf. Until 1961 the two artists published in total three editions of the magazine ZERO.
From 1964 until 1966 he spent some time in New York. After his return the last ZERO group exhibition took place, after which they finally disbanded. In the 1970s and 80s he applied himself overridingly to creating monumental outdoor sculptures and the design of public squares (e.g.: Jurgen-Ponto-Platz in Frankfurt a.M.) as well as stage sets for theatre and opera. In 1991 he developed, for the first time in years, large-format painted pictures.