Orthogonikleithrus is a genus of extinct ray-finned fish that lived during the Late Jurassic period.

It lived in lagoonal and restricted shallow subtidal zones.

The type specimen Orthogonikleithrus leichi was described by G. Arratia in 1987, placing it into the Orthogonikleithridae family.

These specimens were collected during excavations in Cerin by the Université Claude Bernard, Lyon.

The new species is superficially similar to Orthogonikleithrus hoelli but differs in several anatomical features, such as the presence of teeth, the number of tubules in the cephalic lateral line system, and the number of hypurals and uroneurals.