Zahhāk or Zahhak , also known as 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 (going under the name Aži Dahāka) is considered the son of Ahriman, the foe of Ahura Mazda. In the Shāhnāmah of Ferdowsi, Zahhāk is the son of a ruler named Merdās.
The original meaning of dahāka is uncertain. Among the meanings suggested are "stinging" (source uncertain), "burning" (cf. Sanskrit dahana), "man" or "manlike" (cf. Khotanese daha), "huge" or "foreign" (cf. the Dahae people and the Vedic dasas). In Persian mythology, Dahāka is treated as a proper noun, while the form Zahhāk, which appears in the Shāhnāme, was created through the influence of the unrelated Arabic word ḍaḥḥāk meaning "one who laughs".