Ampheristus is an extinct genus of prehistoric marine ray-finned fish. It was a basal or stem member of the family Ophidiidae, which contains modern cusk-eels. Fossils are known from worldwide (the United States, Europe, India, and New Zealand) from the Late Cretaceous to the late Paleogene (Maastrichtian to Oligocene), making it a rather successful survivor of the Cretaceous-Paleogene extinction event. It is one of the oldest known members of the order Ophidiiformes alongside Pastorius from the Maastrichtian of Italy. Only the type species, A. toliapicus from the London Clay, is known from body fossils; the rest are known only by the genus's distinctive otoliths.

Species

The following species are known: The species A. lerichei, known by a body fossil from the Eocene of Belgium and otoliths from the same region, is alternately placed in Ampheristus or Hoplobrotula.