Hans Karl Kaiser (1911-1985) was a German writer who worked both as a science populariser and as a pulp science-fiction novelist (under several pseudonyms: Thomas Hellberg, Richard Oliver, J. R. Richard, R. J. Richards). Around 1949-1950 he published with Mundus-Verlag in Stuttgart a series of small handbooks introducing readers to spaceflight, including Kleine Raketenkunde (1949), translated into French in 1954 by Amiot-Dumont. He returned to the subject with Der künstliche Mond (Thienemann, 1958) and later contributed popular astronomy titles to the Kosmos series (Planeten und Monde, 1960). His correspondence with Willy Ley places him within the network of West German astronautics publicists of the early postwar period. His output is squarely in the popular-science register, with no original scientific contribution.