Bendenius is an extinct genus of prehistoric marine ray-finned fish. It is known from the Early Carboniferous of Belgium. It was named after Belgian paleontologist Pierre-Joseph van Beneden. It contains two species: Formerly classified as a "paleonisciform", more recent studies suggest that it belongs to an early order of deep-bodied actinopterygians known as the Eurynotiformes. It is generally classified within the Styracopteridae, though at least one recent study treats it as a member of the Amphicentridae.