The main aim of my study is to analyse the origins and evolution of Alexander’s legendin the Islamic world and especially in the Persian speaking realms. My starting point isthe Greek Alexander Romance that was most probably written in Alexandria of Egypt;in this article I try to follow the spreading of Alexander’s legend that stems from Pseudo-Callisthenes’s Greek Alexander Romance into the world of the Near East and Middle East.The successive transformations suffered by the figure of Alexander in the Syriac, MiddlePersian (Sassanian Pahlavī), and Arabic Islamic literature have formed the basis for thecreation of Alexander’s figure of a rightful Persian “King of kings”, as it appears into theepic poems of Firdousi and Nizami. However, underground this official image of IskandarDhū-l Qarnayn (‘the Two-Horned Alexander”) or simply Sikandar in the new Persian languageevolved after the Arab Islamic conquest of Iran, there was another strand of Iraniantradition about Alexander of Macedon, namely the Zoroastrian tradition that perceivedthe Macedonian hero as a destroyer of the “Good Religion” and of the true Kings and nobilityof Iran; in short the Macedonian conqueror was seen by them as a wrathful demon.This image of the bad or accursed “Alexander the Roman” is constructed according to theZoroastrian religious principles: the true Iranian Kings ruled through the grace of thesupreme creator God, the righteous and good Deity Ahura-Mazdā (Ormazd/Ormuzd);Alexander appears here more of a destroying entity of the race sprung from the Evil One(Angra Mainyu/Ahriman). This image of an evil “Alexander the Greek/Macedonian/Roman”,was further strengthened by the never ending conflicts between the Parthian ArsacidKingdom and the Seleucid Kingdom, then from the struggle between Parthia andRome, and finally by the wars fought between Sassanian Persia and the Eastern RomanEmpire. It has nevertheless influenced as a Zoroastrian background the image of the goodShahanshah Sikandar (the good “King of kings” Alexander) in the Persian epic poems(Firdousi’s Shah-Name and Nizami’s Iskandar-Name). Another important part of this study is the discussion on the origins of somefigures that appear linked to Alexander in the Islamic legends: the mysterious figureof Dhū-l Qarnayn (“The Two-Horned One”) that appeared in the 18th Chapter(Surah Al-Kahf) of the Koran and that was later identified by the Hadith (theCommentaries to the Koran) and by Islamic scholars with Alexander of Macedon,but also with other royal and prophetic figures from the Pre-Islamic Arabic andPersian past. It was also of special importance the bound formed during Iskandar’s(Alexander’s) quest for the “Fountain of Life” (the Alexander counterpart to theGrass or Herb of Immortality searched by Ghilgamesh, King of Uruk) with the“Green Man” of Islam, Al-Khadir. The mythological and religious underground ofboth Dhū-l Qarnayn’s and Al-Khadir’s figures is underlined by this article of mine.