Prion diseases encompass a diverse group of lethal neurodegenerative disorders associated with the accumulation of misfolded conformers of the prion protein (PrP) in brain neurons. Modeling these diseases in mice and hamsters has led to major advances in our understanding of prion transmission and pathogenesis. However, laboratory rodents are also expensive, time-consuming, and limiting for systematic studies. Genetically tractable animal models, such as the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the zebrafish Danio rerio, have recently made significant contributions to PrP pathogenesis. Here, we discuss recent applications of these three nonmammalian models to various relevant areas, including PrP processing, trafficking, misfolding, neurotoxicity, as well as unraveling its elusive endogenous function. Now that these alternative models have staked a claim on PrP biology, we anticipate that they will expand their range of applications and contributions in the next few years, including the generation of nonmammalian models of prion transmissibility.