Phodopus, a genus of rodents in the hamster subfamily Cricetinae—a division of the larger family Cricetidae—is a lineage of small hamsters native to central Asia that display unusual adaptations to extreme temperatures. They are the only known hamsters that live in groups and, in some cases, rely on significant contributions by males to the raising of offspring. They are nocturnal and active throughout the year; they do not hibernate. Species of Phodopus, together with members of the genera Cricetulus, Allocricetulus and Tscherskia are called dwarf hamsters because of their small size relative to other hamsters.

The European hamster, also known as the Eurasian hamster, black-bellied hamster or common hamster, is the only species of hamster in the genus Cricetus. It is native to grassland and similar habitats in a large part of Eurasia, extending from Belgium to the Altai Mountains and Yenisey River in Russia. Historically, it was considered a farmland pest and had been trapped for its fur. Its population has declined drastically in recent years and is now considered critically endangered. The main threats to the species are thought to be intensive agriculture, habitat destruction, and persecution by farmers.