Ariaethus or Araethus (Ancient Greek: Ἀρίαιθος, Ariaithos or Araithos) was a writer from the ancient Greek city-state of Tegea, whose work survives in fragments. The most notable known work by this author was Arkadika, which focused on local myths in Arcadia.[1][2][3] This also includes myths dealing with local affairs in Tegea. The date of his writing is unknown, but it has been suggested that he wrote either in the 4th century BC or the 3rd century BC.[4] Madeleine Jost and James Roy propose the Hellenistic period to be the most likely due to the inclusion of Aeneas in one of the fragments.[5] It is uncertain whether his work included later Arcadian history as well as the mythical past. His account is unique in that it is an account of Arcadian traditions by an Arcadian writer, making the fragments of his work essential for our understanding of Arcadian history.