The Greek lamprey (Caspiomyzon hellenicus) (also known as the Greek or Macedonia brook lamprey) is a species of jawless fish in the Petromyzontidae family. It is endemic to Greece. Its natural habitats are rivers and freshwater springs. It is threatened by habitat loss. Originally considered a species of the genus Eudontomyzon, later phylogenetic analyses suggested that a placement within Caspiomyzon was more likely. It is the most endangered species of lamprey, living only in the Strymon and Louros river basins.