Fruiting bodies or sporocarps of dikaryotic (ascomycetous and basidiomycetous) fungi, commonly referred to as mushrooms, are often rich in entomotoxic and nematotoxic proteins that include lectins and protease inhibitors. These protein toxins are thought to act as effectors of an innate defense system of mushrooms against animal predators including fungivorous insects and nematodes. In this review, we summarize current knowledge about the structures, target molecules, and regulation of the biosynthesis of the best characterized representatives of these fungal defense proteins, including galectins, beta-trefoil-type lectins, actinoporin-type lectins, beta-propeller-type lectins and beta-trefoil-type chimerolectins, as well as mycospin and mycocypin families of protease inhibitors. We also present an overview of the phylogenetic distribution of these proteins among a selection of fungal genomes and draw some conclusions about their evolution and physiological function. Finally, we present an outlook for future research directions in this field and their potential applications in medicine and crop protection.