Before flying saucers, robot monsters, and alien menaces invaded the movies of the 1950s, there was already a significant body of animated science fiction, produced by such studios as Disney, the Fleischers, and Terrytoons. That work has largely been overlooked or forgotten, despite the fact that the same pre-World War II era that produced this group of short films also saw the more prominent development and flourishing of SF as a literary genre. This book surveys that neglected body of work to show how it helped contribute to the burgeoning SF imagination that was manifested in pulp literature, serials, feature films, and even World’s Fairs of the era. It argues that prewar cartoons helped to create a familiarity with the scientific and technological developments that were spurring that SF imagination and build an audience for this new genre. Demonstrating the same modernist spirit as SF literature and feature films, these cartoons adopted many of the genre’s most important motifs (rockets and space travel, robots, alien worlds and their inhabitants, and fantastic inventions and inventors), offered comic visions of the era’s growing fascination with science and technology, and framed that matter in a nonthreatening fashion. Popular animation thereby not only added another dimension to the SF imagination, but also helped prepare postwar audiences to embrace SF’s vision of the future and of inevitable change.