- Zarathustra (directly from Avestan)
- Ancient Iranian prophet after whom indigenous Iranian ethnic religion is named Zoroastrianism
- Pseudepigraphic name used by various Ancient Greek and Latin authors of late antiquity to lend their opinions weight.
- (Can we clean up(+) this sense?) Ostensible source/founder of Mithraism, the "mysteries" of the Roman Mysteriae Mithrae ("Mysteries of Mithras", "Mithraic Mysteries"), an astrology-centric, middle-platonic mystery cult of the 1st-4th century Roman Empire whose adherents worshiped in "caves" (i.e. Mithraea) in imitation of "Zoroaster". (Porphyry, De Antro Nympharum 6)
founder of Zoroastrianism