Harun al Rashid

Abu Ja'far Harun ibn Muhammad al-Mahdi or simply Harun ibn al-Mahdi, famously known as Harun al-Rashid was the fifth Abbasid Caliph who ruled during the golden age of Islam, he was a pious, warrior and philosopher-King.
Harun established the legendary library Bayt al-Hikma ("House of Wisdom") in Baghdad in present-day Iraq, and during his rule Baghdad began to flourish as a world center of knowledge, culture, and trade. The splendor of his court reached far and wide, that the King of the Franks, Charlemagne also known as the father of Europe had sent embassies to Harun, and in turn, Harun sent him exotic gifts.
If one were to westernized his name it would've been Aaron the Just.