The end of the 19th century is strongly marked by the discoveries of Pasteur and the development of the germ theory of contagious diseases. Our paper briefly presents the introduction of microbe into scientific-marvelous novels, and then analyzes its attack in Charles Épheyre’s short story, Le Microbe du professeur Bakermann (1890), as well as the unexpected appearance of macrobes in André Couvreur’s novel, Une Invasion de Macrobes (1909). Professors Bakermann and Tornada are reminiscent of demiurges caught up in the frenzy of glory and power. Will they finally be able to destroy the human race, thereby ruining the ethos of a scientist? We will attempt to parallel their destinies in order to show the danger posed by excessive ambitions combined with uncommon intelligence. Fallen unjustly into oblivion, both texts deserve to be rediscovered due to the exceptional apocalyptic vision which they depict.