Ahura Mazda is the deity named repeatedly as the supreme god in Achaemenid royal inscriptions.
Kings including Darius I and Xerxes I credited Ahura Mazda with granting them kingship and helping them defeat rebellion. The formula appears in inscriptions at sites such as Behistun, Persepolis, and Naqsh-e Rustam.
Ahura Mazda is central to Zoroastrian tradition, but the religious practices of the Achaemenid period were varied. The empire ruled many peoples and generally allowed local cults to continue, so royal references to Ahura Mazda did not erase other important deities.
Mithra and Anahita were also worshipped in the Iranian world. Marduk, by contrast, was the major god of Babylon. These distinctions matter because Achaemenid inscriptions often connected Persian kingship with Ahura Mazda while acknowledging the empire’s broader religious landscape.