Person
Muslim tradition has often identified him with Dhu al-Qarnayn, but the Quran does not name him.
What it means
Chapter 18 tells of Dhu al-Qarnayn, “the two-horned one”, a righteous ruler who travelled west and east and built a barrier against Gog and Magog (18:83–98). The Quran gives no name. Many early commentators, influenced by the Alexander legend, thought it was Alexander; others suggested a South Arabian king or a Persian ruler such as Cyrus.
Often misunderstood as
That the Quran calls a pagan conqueror a believing Muslim.
What the sources say
The Quran describes only a ruler who is told to deal justly, believes in God, and says of the barrier “this is a mercy from my Lord” (18:98). Nothing there requires him to be Alexander, and Muslim scholars have long said the identity is uncertain.