Companions & Great WomenA figure of the Quran
ذو القرنين
A righteous king whom Allah established in the earth, who reached the far west and east and built the barrier against Ya'juj and Ma'juj.
When the Prophet ﷺ was asked about Dhul-Qarnayn, he was told to recite a remembrance of him (18:83): Allah established him in the earth and gave him means to everything, and he followed them to the setting of the sun and its rising, and built a barrier against Ya'juj and Ma'juj. As-Sa'di notes that Allah and His Messenger have not told us what those means were, so we keep silent about them rather than follow the reports of the People of the Book.
islamweb's fatwa says he was a righteous king who worshipped Allah, as the Quran shows, and that the Prophet ﷺ said he did not know whether he was a prophet. Another fatwa quotes Ibn Taymiyyah that he was not Alexander of Macedon: he lived long before him and worshipped Allah alone, and no text gives his origin or lineage.
وَيَسْـَٔلُونَكَ عَن ذِى ٱلْقَرْنَيْنِ ۖ قُلْ سَأَتْلُوا۟ عَلَيْكُم مِّنْهُ ذِكْرًا ٨٣
And they ask you, [O Muḥammad], about Dhul-Qarnayn. Say, "I will recite to you about him a report."
Saheeh International · QuranEnc v1.1.2
83. And they ask you about Dhul-Qarnain. Say: "I shall recite to you something of his story."