Ahura Mazda

Question: Who is Ahura Mazda?

Also known as Avestan, meaning 'Wise Lord', Ahura Mazdā is the creator of the universe and the supreme god of the ancient Medes and Persians, and especially of Zoroastrianism, the religion of the prophet Zarathustra (6th century BCE). He was worshipped by Darius I, who ruled Persia from 522-486 BCE, and by his successors as being the greatest of all gods and the protector of the just king/ruler. 

It was believed that Ahura Mazdā is the supreme being in Garothman (heaven), the uncreated spirit, beyond and apart from and without whom, there is no-thing in existence. He is changeless, moving all, while not being moved by anyone and having no equal. He favours the just, upholding truth and proper behaviour.

Worth noting is that the proto-Iranian word Mazdāh, from which the Avestan word Mazda/Mazdā derives, is a feminine noun, meaning (as far as I can discover) Life.

Zoroastrianism was the faith of the Parthian Empire (247-224 BCE) and many temples which had previously been destroyed around 330 BCE by the campaigns of Alexander the Great were rebuilt. The Parthians, however, also tolerated the presence of Hindus, Buddhists, Jews, and Christians, along with elements of Mithraism. During the Sassanid period (224BCE -651 CE) Zoroastrianism and the worship of Ahura Mazdā as the supreme being was succeeded by Zurvanism, Ahura Mazdā being re-named Ohrmazd-mowbad, and down-graded to a son of Zurvan alongside Ahriman/Angra Mainya.