Enrico Castellani (1930, Castelmassa – 2017, Viterbo) was one of the most influential Italian Avant-garde artists. He is associated with the ZERO movement and Azimuth.

Castellani studied sculpture and painting at Académie Royale des Beaux-Arts in 1952 and architecture at École nationale supérieure des Beaux-Arts in Belgium (1956).

Following his return to Italy, he collaborated with artists such as Lucio Fontana and Piero Manzoni. With Manzoni, in 1959, Castellani founded the Milan gallery Azimut and the affiliated journal Azimuth. The gallery featured thirteen exhibitions, such as those of Piero Manzoni, Enrico Castellani, Heinz Mack, Almir Mavignier, Alberti Sordini Verga and several group exhibitions.

He was an active member of the ZERO group, a loosely connected group of artists. Heinz Mack, Otto Piene, and Günther Uecker began the ZERO movement. Other key members were from France (Arman, Jean Tinguely, Yves Klein, and Bernard Aubertin), Italy (Lucio Fontana, Piero Manzoni), Belgium (Pol Bury, Jef Verheyen, Walter Leblanc), the Netherlands (Henk Peeters, Herman de Vries) and Switzerland (Christian Megert).

His style is characterised as merging art, spatiality and architecture. In 1959 Castellani created his first painting in relief. In his relief paintings (Superfici), he fastened canvases over protruding nails, giving the works a perspective of light and shade, positive and negative space. His monochrome stretched canvases are white, yellow, black, blue and red. Castellani's work deals with the sculptural aspects of constructing a painting. With that, it fits into the ZERO Avant-garde group goal to focus on materiality. Castellani also designed sets for theatre and ballet productions. He also created installations, or environments, placing his works strategically in a gallery.

Castellani's essay Continuità e nuovo (1960), published in the Azimuth magazine's second issue shows his wish to disassociate from Tachisme and Art Informel and embrace new artistic styles.