Josip Seissel (10 January 1904 – 19 February 1987) was a Croatian architect and urban planner, who under the pseudonym of Jo Klek was a constructivist artist, graphical designer and theatrical designer. A member of the influential avant-garde Zenit movement of the 1920s, he is considered to be a pioneer of surrealism and abstract art in Croatia. In 1969, he received the Vladimir Nazor Award for lifetime achievement in architecture.