Zoroaster (zōrˈōăsˌtər) [key], c.628 B.C.–c.551 B.C., religious teacher and prophet of ancient Persia, founder of Zoroastrianism. Zoroaster, the name by which he is ordinarily known, is derived from the Greek form of Zarathushtra (or Zarathustra) [camel handler?], his Persian name. Zoroaster is believed to have been born in NW Persia. His youthful studies were crowned at the age of 30 by the first of a series of revelations of a new religion. His attempts to proselytize at home failed, and he fled east to ancient Chorasmia (now largely Iranian Khorasan), where he converted King Vishtaspa (who may have been Hystaspes, the father of Darius). The religion then spread rapidly through Vishtaspa's domain. The circumstances of Zoroaster's death are not known.
See E. Herzfeld, Zoroaster and His World (1947); R. C. Zaehner, The Dawn and Twilight of Zoroastrianism (1961).