The black rat (Rattus rattus) is among the world’s worst invasive species, having spread across the globe in close association with the spread of human settlement. It is the source of some of the worst diseases affecting humans and is thought to have had a devastating impact on native wildlife, especially in island ecosystems. Black rat is likely to have arrived in Australia with the first European settlers, making it among the first of many alien species to invade the continent, and it is now widespread. Yet, its impacts on local wildlife have largely been overlooked. Here, we review the potential for black rat impacts in Australia in terms of its role as a source of disease and threats to wildlife and humans. We first summarise the global evidence for black rat impacts as background to the potential threats it poses and then focus specifically on emerging evidence available for Australian systems. We found a significant gap in our understanding of the ecology of black rats and the ecological role that it plays in Australia. This is despite its role as a source of a diverse range of diseases affecting humans and wildlife and its actions as a predator and competitor of native wildlife in Australia and elsewhere.