The killer shrimp (Dikerogammarus villosus) is an invasive freshwater amphipod in the UK, first recorded in 2010. Native to the Ponto-Caspian region, it has spread rapidly through European waterways via ballast water and recreational equipment. This highly aggressive species preys on a wide range of invertebrates and fish eggs, earning its name for its destructive impact on aquatic ecosystems. By outcompeting and preying on native species, it significantly disrupts food webs and reduces biodiversity.