Eoeugnathus (Greek for "dawn true-jaw") is an extinct genus of prehistoric marine ray-finned fish belonging to the Halecomorphi. Eoeugnathus existed during the Middle Triassic in what is now Europe.
It contains two species:
It was initially placed in the Caturidae and then the Panxianichthyiformes, but more recent studies have placed it in the new ionoscopiform family Subortichthyidae.