What is the name of the supreme god in Zoroastrianism?

The supreme god in Zoroastrianism is Ahura Mazda.

The name comes from Avestan: ahura means “lord,” while mazda is associated with wisdom. Zoroastrian teaching presents Ahura Mazda as the creator and sustaining power of the universe, connected with truth, goodness, and the cosmic order called asha. Zoroaster’s hymns, the Gathas, describe him as the highest divine being and the source of moral insight.

Ahura Mazda is sometimes confused with Mithra, Rashnu, or Vayu. Those are important figures in the broader Zoroastrian religious world, but they are not the supreme god. Mithra is associated with covenants and justice, Rashnu with judgment, and Vayu with the wind. Angra Mainyu, or Ahriman in later Middle Persian tradition, is also not a rival god of equal status in every Zoroastrian interpretation; he represents destructive evil.

The deity appears in ancient Persian royal inscriptions, especially those of the Achaemenid king Darius I. Later forms of the name include Ohrmazd and Ormazd.