Al Fadl Ibn Al Rabi (الفضل بن الربيع), who lived from around A.D. 757 to 823, was a powerful minister of the Abbasid Caliphate in Baghdad.  He served the caliphs Harun Al Rashid and Al Amin, the sixth Abbasid ruler.  It was during his tenure in office that the caliphate descended into civil war.