The genus Cybister Curtis (Coleoptera: Dytiscidae) in the Nearctic region is reviewed including taxonomic history, keys to species, diagnoses, illustrations, distributions, and natural history. Three species are recognized in the genus. Cybister explanatus LeConte, 1852 (= Cybister explanatus laevicollis Zimmermann, 1919; = Cybister explanatus fusculus Zimmermann, 1919) is found from southern Oregon through California and Nevada and through western Mexico to Chiapas. Cybister occidentalis Aubé, 1838 is found in Cuba, the Bahamas, and extreme southern Florida. Cybister fimbriolatus (Say, 1823) (= Cybister dissimilis Aubé, 1838; = Cybister flavocinctus Aubé, 1838 new synonymy; = Cybister ellipticus LeConte, 1852 new synonymy; = Cybister cavicollis Sharp, 1887 new synonymy; = Cybister crotchi Wilke, 1920) is found from southeastern Canada west to Ontario and North Dakota south through eastern North America to Florida and the Bahamas (Bahimi Island), west through the southern United States to Arizona and southern California and south throughout Mexico to the Yucatán. Lectotypes are designated for C. ellipticus and C. explanatus.