Recent conservation assessments rank the world's freshwater crayfish in the five most endangered animal groups, and the Australian fauna as the most endangered of all the world's crayfish. In this paper, we introduce the 135 described species of freshwater crayfish in Australia, and provide an overview of this fauna and their current IUCN Red List conservation status. The Australian crayfish fauna is almost entirely endemic, and displays enormous variation in biology, distribution and ecology. Some Australian species are the world's fastest growing, most highly fecund and widely distributed crayfishes, and are tolerant of extreme variation in environmental conditions. Conversely, Australia is also home to many crayfish that are remarkably slow growing, late maturing and poorly fecund. Many species have highly restricted distributions and require specific environmental conditions that restrict them to particular areas and habitat types. These crayfish face a wide range of existing and emerging threats, and we discuss the research imperatives, practical actions, legislative changes and collaboration required to facilitate the recovery of crayfish populations.