Spermophilus or Citellus is a genus of ground squirrels in the family Sciuridae (rodents). The majority of ground squirrel species, over 40 in total, are usually placed in this genus. However, Spermophilus in the broad sense has been found to be paraphyletic to the certainly distinct prairie dogs, marmots, and antelope squirrels, so it has been split into several genera by Kristofer Helgen and colleagues.
Some Eurasian species are sometimes called susliks (or sousliks). This name comes from Russian суслик, suslik. In some languages, a derivative of the name is in common usage, for example suseł in Polish. The scientific name of this genus means "seed-lovers" (gr. σπέρμα sperma, genitive σπέρματος spermatos – seed; φίλος philos – friend, lover).
Ground squirrels may carry fleas that transmit diseases to humans (see Black Death), and have been destructive in tunneling underneath human habitation. Though capable of climbing, most species of ground squirrel live in open, treeless habitats.