Axius (Greek: Ἀξιός) is a Paeonian river god, the son of Oceanus and Tethys. He was the father of Pelagon, by Periboea, daughter of Acessamenus. His domain is the river Axius, or Vardar, in Macedonia (region).
The river god is ancestor of Euphemus and his son, Eurybarus, the hero who slew the drakaina Sybaris.