For the Slovak art of the Sixties, as well as for following decades, the subject of space is significant. Unlike in the other Eastern European countries, the situation in Slovakia was specific because the subject has profoundly affected not only mass culture, but also the sphere of a progressive (and, therefore, non-official) visual art. The goal of the paper is to compare the artworks of two important representatives of the Slovak neo-avant-garde, let us say the part of their work which is connected to the subject of space and related topics (such as cosmonautics, extraterrestrials, etc). The two artists in question are Stanislav Filko (1937) and Július Koller (1939–2007). Although Filko and Koller are diametrically different in many aspects, they represent good ‘comparative material,’ because apart from the subject of space there is another important feature that they have in common — an overall fusion of their artistic work and personal life.