Answer
There were many famous historical personalities by the name of Alexander (Sikander). The one generally referred to as ‘Alexander the Great’ was a Greek commander who was a Mushrik (polytheist). He also was the student of the famous greek philosopher Aristotle. It is established from the Qur’aan that Dhul-Qarnayn was a pious Muslim, and according to some, he was a Prophet. Therefore, Dhul Qarnayn was not ‘Alexander the Great’. According to the renowned Mufassir, Ibn Kathir, Dhul Qarnayn was Alexander who appeared approximately 2000 years before ‘Alexander the Great’ (Ma’ariful Qur’aan vol.5 pg.618) From: Al Mahmood 13 Q & A from the Darul Ifta Mufti Ebrahim Desai