Đuro Seder (born 29 November 1927 in Zagreb) is a Croatian painter. He lives and works in Zagreb, Croatia. At the beginning of his career he worked as an illustrator, image editor and designer at various magazines. He was one of the founding members of the Gorgona Group, whose active members between 1959 and 1966 were Miljenko Horvat, Ivan Kožarić, Julije Knifer, Dimitrije Bašičević (who also worked under the name Mangelos), Matko Meštrović, Radoslav Putar, Marijan Jevšovar and Josip Vaništa. During the Gorgona period he was more active in the group than with solo presentations, and his work was marked by the informel-influenced disintegration of form, negation of traditional painting techniques and reduced use of colours, which can be seen for example in his works, Anonymous Form, (1963)