Amphion (; Ancient Greek: Ἀμφίων, romanized: Amphíōn) and Zethus (; Ancient Greek: Ζῆθος, romanized: Zêthos) were, in ancient Greek mythology, the twin sons of Zeus (or Theobus) by Antiope. They are important characters in one of the two founding myths of the city of Thebes, because they constructed the city's walls. Zethus or Amphion had a daughter called Neis (Νηίς), and the Neitian gate at Thebes was believed to have derived its name from her.