Genethlius (Greek: Γενέθλιος, romanized: Genéthlios) was a 3rd-century Arab sophist from Petra, Arabia Petraea.
His father was also named Genethlius.
[1] He was a pupil of the Greek sophists Minucianus (Ancient Greek: Μινουκιανός) and Agapetus (Ancient Greek: Ἀγαπητός), and then he himself became a teacher and practiced rhetoric in Athens.
He has been known as a rival to the famous Callinicus of Petra.
[2][3] Genethlius is also thought by some scholars to be the author of the first treatise in the corpus of Menander Rhetor.