Edestus is a genus of eugeneodontid holocephalids that lived throughout the world's oceans from the Late Devonian to the late Carboniferous. All of the species are known only from their teeth. The term "edestid" is often used to refer to any or all members of the order Eugeneodontiformes, though, strictly speaking, "edestid" properly refers only to members of the family Edestidae. Edestus is a Greek name derived from the word edeste, in reference to the aberrant quality and size of the species' teeth. The largest species, E. giganteus, could reach 6 m in length, the size of a modern great white shark.