Zarathustra

n. Persian philosopher from the 6th century BC (introduced reform and change into religious belief and liturgy)

Zoroaster (Greek Ζωροάστρης, Zōroastrēs) or Zarathustra (Avestan: Zaraθuštra), also referred to as Zartosht ( ;  Kurdish: ), was an ancient Iranian prophet and religious poet. The hymns attributed to him are the scriptural basis of Zoroastrianism. Zoroaster is generally accepted to be an authentic historical figure.
See more at Wikipedia.org...

Noun
1. Persian prophet who founded Zoroastrianism (circa 628-551 BC)
(synonym) Zoroaster
(hypernym) prophet

n. Zoroaster, father of ancient Persian religion

[Persian] The traditional founder and prophet of Zoroastrianism, the dualistic religion of ancient Persia based upon the struggles between the good and evil principles represented by Ahura Mazda and Ahriman. Likely, Zarathustra was a religious leader who reorganized and reconstituted an older faith. The Zend-Avesta, the sacred writings of the Zoroastrian religion, is purposed to be a collection of his writings. He is also referred to as Zoroaster, which is Greek rendering of his name.