Aži Dahāka

Azi Dahaka appears in the Avesta as the most formidable of the created evils, a three headed, three jawed, six eyed serpent whose name simply means dragon, Dahaka. The Aban Yasht, the hymn to the waters and to the goddess Anahita collected as Yasht 5, has the hero Thraetaona pray to her for the strength to overcome him, and the same hymn credits Azi Dahaka himself with seeking her favor first, for power to depopulate the world of its people, a request the text has Anahita refuse. Thraetaona ultimately defeats the creature, though later tradition holds he does not kill it outright but binds it, commonly located at Mount Damavand in later Persian geography, where it is said to remain chained until it breaks free at the end of days as one of the final evils the world must face before its renewal.

The creature functions in Avestan cosmology as druj incarnate, the Lie given monstrous form, set against Ahura Mazda's order the way every major demon in the Zoroastrian scheme personifies a specific corruption of a specific good. Azi Dahaka's association with drought, death and the extinguishing of legitimate kingship recurs through the textual tradition and carries directly into the creature's later, far more famous incarnation.

By the time Ferdowsi composed the Shahnameh, the Persian national epic completed around 1010 CE, Azi Dahaka had been reworked into Zahhak, a human tyrant rather than a cosmic serpent outright, though the serpents remain: two snakes said to grow from his shoulders after a kiss from Ahriman's agent, each demanding to be fed a human brain daily to keep from devouring Zahhak himself. Zahhak seizes the throne from the legitimate king Jamshid, whose own story the Avesta and the Bundahishn preserve independently as Yima, and rules as a monster of misrule until the blacksmith Kaveh raises a rebellion and the hero Fereydun, a continuation of the Avestan Thraetaona under a later name, overthrows him and binds him at Mount Damavand.

The transformation illustrates how a single mythic structure, a chaos serpent whose defeat restores rightful order, persisted across more than a thousand years and a shift from religious scripture to secular epic, carrying its core opposition essentially unchanged while its surface details, name and genre all changed around it. Mary Boyce and later historians of Iranian religion treat the Avesta to Shahnameh transmission of Azi Dahaka or Zahhak as one of the clearest cases of Iranian religious myth surviving Islamic conversion by migrating into national literature rather than continued cultic practice.