Zarathustra
From ReformedWiki.org, the wiki for Reformed Christianity
Zarathustra (also known as Zoroaster) was the, possibly fictional, founder of the non-Christian monotheistic Zoroastrian religion.
According to legends, once during a spring festival he was walking along a river when he received a revelation from the one true God, known as Ahura Mazda, and was instructed to abandon paganism and found Zoroastrianism.
