Saoshyant is in Zoroastrianism the World Savior. During the period which was the dark years of the religion the belief in a savior emerged. Gathic passages suggest Zoroaster was filled with a sense of the imminent end of the world which caused him to envision Ahura Mazda sending “a man who is better than a good man” (Y 43.3), the Saoshyant, literally meaning “one who will bring benefit,” who will possess revealed truth and will lead humanity in the final battle against evil. It is probable that Zoroaster realized that he was not going to live to see the age of Frasho-kereti. His followers ardently clung to this expectation, coming to believe that Saoshyant would come from the prophet’s own seed, miraculously preserved in the depths of a lake (identified as Lake Kasaoya). When the end of time approaches, it is said, a virgin will bathe in this lake and become with child by the prophet, and she will in due course bear a son, named Astvat-ereta, “He who embodies righteousness” (after Zoroaster’s own words: “My righteousness embodied” Y 43.16).
Despite of his miraculous conception, Saoshyant will be born of human parents according to Zoroaster’s teachings. Saoshyant will participate in the cosmic struggle, being accompanied by kings and heroes, and by Khvarenah. Avesta gives the most detailed account: “When Astvat-ereta comes from the Lake Kasaoya, messenger of Ahura Mazda…then he will drive the Drug out from the world of Asha.” Such a glorious moment was eagerly hoped for by the faithful, and this hope was to be their strength and comfort in adverse times.
According to other mythological traditions Saoshyant, or Saoshyans, is referred to in the plural indicating the religious and other leaders. “The first to be summoned by man, fire, water, and plants to oppose Dahaka is Thraetona (Freifoun). Dahaka (later Zohak), a tyrannical king on whose shoulders grow two voracious serpents, is the symbol of violent, orgiastic kingship destroying the “elements.” Thraetina does not prevail and recourse is taken to another hero, Sam Kersasp, son of Mariman, who puts Dahaka to death. Then after a long period of ruling over the world, Kersasp hands to Kay Husroy, who governs with Saoshyans (representing religious tradition) as his great mobed (chief of the ecclesiastical hierarchy). Kay Husroy is succeeded by the first Mazdaen king, Vishtasp, and Saoshyans by the founder of the religion, Zarasthustra” A.G.H.
Boyce, Mary, Zoroastrians: Their Religious Beliefs and Practices, New York, Routledge, 2002, p. 42
Grimal, Pierre, Larousse World Mythology, Secaucus, New Jersey, Chartwell Books, 1965, p. 199