Zahhāk or Zahāk, also known as Zahhak the Snake Shoulder, is an evil figure in Persian mythology, evident in ancient Persian folklore as Azhi Dahāka, the name by which he also appears in the texts of the Avesta. In Middle Persian he is called Dahāg or Bēvar Asp the latter meaning "he who has 10,000 horses". In Zoroastrianism, Zahhak is considered the son of Ahriman, the foe of Ahura Mazda. In the Shāhnāmeh of Ferdowsi, Zahhāk is the son of a ruler named Merdās.

Zoroastrianism, also known as Mazdayasna and Behdin, is an Iranian religion. One of the world's oldest organized faiths, it is based on the teachings of the Avesta and the Iranian prophet Zoroaster. Zoroastrians exalt an uncreated and benevolent deity of wisdom, commonly referred to as "Ahura Mazda", as the universe's supreme being; opposed to Ahura Mazda is "Angra Mainyu", who is personified as a destructive spirit and the adversary of all things good. Zoroastranism combines a dualistic cosmology of good and evil with an eschatology predicting the ultimate triumph of Ahura Mazda over evil. Opinions vary among scholars as to whether Zoroastrianism is monotheistic, polytheistic, or henotheistic. Some assert that it combines elements of all three.