Otto Piene was a German artist and co-founder of the artist group ZERO. He is considered a pioneer of light and fire art as well as sky art actions. As a reaction to abstract Informel, Piene founded the later internationally influential artist group ZERO (“Zero Point of Art”) together with Heinz Mack in Düsseldorf on April 11, 1957, which Günther Uecker also joined in 1961.