Hexanchus is a genus of six-gilled sharks. Compagno (1984) considered two species to be valid, Hexanchus vitulus SPRINGER & WALLER 1969 a circumglobal (spotty and not in the eastern Pacific) warm temperate to tropical species, and the larger (to 4.8 m) Hexanchus griseus (BONNATERRE, 1788). The later species is wide ranging and inhabits similar waters, circumglobally. Compagno points out that H. griseus has six files of the "comb-like" lateral teeth per side, while H. vitulus has only five.