Al-Hasan Al-Basri said: He had two braids of hair that he used to fold up and thus was called "Dhul-Qarnain". And, Ishaq Ibn Bishr narrated that the grandfather of 'Umar Ibn Shu' aib said: DhulQarnain, once, invited a tyrant king to the way of Allah. The king hit him on the head and broke one of his horns. Dhul-Qarnain invited him again and the tyrant broke the second horn. Thus, he was called "Dhul-Qarnain" .
Narrated Ath-Thawri that 'Ali Ibn Abu Talib (May Allah be pleased with him) was once asked about Dhul-Qarnain. He replied saying: He was a rightly-guided and pious man. He invited his people to Allah, but they hit him on his horn (side of the head) and he was killed. Allah the Almighty resurrected him and he invited them again, again they hit him on his second horn and he was killed (for the second time). Allah the Almighty revived him and thus he was called "DhulQarnain". In other narrations, it was narrated by Abu At-Tufail after 'Ali Ibn Abu Talib that he said: He was neither a Prophet, nor a Messenger, nor an Angel, but was a godly, pious worshipper.
What's his Name?
Scholars disagreed regarding his name. Az Zubair Ibn Bakkar narrated after' Abdullah Ibn, Abbas (May Allah be pleased with him): His name was 'Abdullah Ibn Ad-Dahhak Ibn Ma'd; or Mus'ab Ibn 'Abdullah IbnQinan Ibn Mansur Ibn 'Abdullah Ibn Al-Azd Ibn Ghauth Ibn Nabt Ibn Malik Ibn Zaid Ibn Kahlan Ibn Saba' Ibn Qahtan.
It has been narrated in a Hadith that he was from the tribe of Himyar and that his mQther was Roman, and he was called the Philosopher for the excellence of his mentality. However, As-Suhaili said: his name was Marzaban Ibn Marzabah. This was mentioned by Ibn Hisham who mentioned in another location that his name was: As-Sa'b Ibn Dhi Mara'id who was the grandfather of the Tababi'ah and it was him who gave the verdict to the benefit of Ibrahim (Peace be upon him) pertaining to the well of As-Sab' .
It was said: He was Afridun Ibn Asfiyan who killed Ad-Dahhak. Al-Qass Ibn Sa' idah Al-Iyadi said in his famous sermon: 0 folk of Ayad Ibn As-Sa'b! DhulQarnain ruled over the west. and east, subjugated the Jinn and mankind, and he lived for two thousand years. However, all this was just like a twinkle of the eye.
Ad- Daraqutni and Ibn Makula mentioned that his name was Hirmis, or Hirwis Ibn Qitun Ibn Rumi Ibn Lanti Ibn Kashaukhin Ibn Yunan Ibn Yafith Ibn Nuh (Noah (Peace be upon him)), and Allah knows best!