Pacifastacus is a genus of crayfish native to western North America (USA and Canada), containing six species, two of which are extinct:
- †Pacifastacus chenoderma (fossil: Miocene – Pliocene)
- Pacifastacus connectens
- Pacifastacus fortis – Shasta crayfish
- Pacifastacus gambelii
- Pacifastacus leniusculus – signal crayfish
- †Pacifastacus nigrescens – Sooty crayfish