According to Shahnameh of Ferdowsi, Rostam-e Dastan is the champion of champions and mythical hero of ancient Persia, constituting some of the most popular parts of the Shahnameh. He is the son of Zal (the son of Sam and the grandson of Nariman). Also, his legend indicates that Rostam's mother is a decedent of Zahhak, the son of Mardas.But in the older version of this myth, Dastan is a title for Rostam, Nariman a title for Garshasb, Mardas a title for Zahhak, and Sam is the name of the extended family of Garshasb.The present paper tries to show that the myth of Rostam has been transformed in Shahnameh.