Cambarus bartonii is a species of crayfish native to eastern North America, where it is called the common crayfish or Appalachian brook crayfish. C. bartonii was the first crayfish to be described from North America, when Johan Christian Fabricius published it under the name Astacus Bartonii in his 1798 work Supplementum entomologiae systematicae. The locality where his specimen was captured is not known, but is thought to be near Philadelphia, Pennsylvania. Colouration is usually plain dark brown, although mottling is occasionally seen, as is a saddle-shaped marking.