Fereydūn (Persian: فریدون) also pronounced (e.g. in Tajik) Farīdūn or (arabicized) Afrīdūn (Medieval Persian: Firēdūn, Middle Persian: Frēdōn, Avestan Θraētaona) is the name of an Iranian mythical king and hero who is an emblem of victory, justice and generosity in the Persian literature.
All of the forms of the name shown above derive, by regular sound laws, from Proto-Iranian *Θraitaunah and Proto-Indo-Iranian *Traitaunas.
*Traitaunas is a derivative (with augmentative suffix -una/-auna) of *Tritas, the name of a deity or hero reflected in the Vedic Trita and the Avestan Θrita. Both names are identical to the adjective meaning "the third", a term used of a minor deity associated with two other deities to form a triad. In the Indian Vedas, Trita is associated with gods of thunder and wind. Trita is also called Āptya, a name that is probably cognate with Āθβiya, the name of Θraētaona's father in the Avesta. *Traitaunas may therefore be interpreted as "the great son of the deity Tritas". The name was borrowed from Parthian into Armenian as Hrudēn.
Θraētaona in Zoroastrian literature 
In the Avesta, Θraētaona is the son of Āθβiya, and so is called Āθβiyāni "from the family of Āθβiya". Originally he may have been recorded as the killer of the dragon Aži Dahāka, but in Middle Persian texts Dahāka/Dahāg is instead imprisoned on Mount Damāvand, Amol.
Fereydun in the Shāhnāmeh 
According to Ferdowsi’s Shāhnāmeh, Fereydun was the son of Ābtīn, one of descendants of Jamshid. Fereydun, together with Kaveh, revolted against the tyrannical king “Zahhāk”, defeated and arrested him in the Alborz Mountains. Afterwards Fereydun became the king and, according to the myth, ruled the country for about 500 years. At the end of his life he allocated his kingdom to his three sons; Salm, Tur, and Iraj. Iraj was Fereydun’s youngest and favored son and inherited the best part of the kingdom, namely Iran. Salm inherited Asia Minor ("Rūm", more generally meaning the Roman Empire, the Greco-Roman world, or just "the West") and Tur inherited Central Asia ("Tūrān", all the lands north and east of the Oxus, as far as China), respectively. This aroused Iraj’s brothers’ envy and encouraged them to murder him. After Iraj’s murder, Fereydun enthroned Iraj’s grandson, Manūchehr. Manūchehr’s attempt to avenge his grandfather’s murder initiated the Iranian-Turanian wars.
- A king's book of kings: the Shah-nameh of Shah Tahmasp, an exhibition catalog from The Metropolitan Museum of Art (fully available online as PDF), which contains material on Fereydun
|Legendary Kings of the Shāhnāma
1800-2300 (after Keyumars)