Rafi ibn al-Layth ibn Nasr ibn Sayyar was a Khurasani Arab noble who led a large-scale rebellion against the Abbasid Caliphate in 806–809.
He was the grandson of the last Umayyad governor of Khurasan, Nasr ibn Sayyar, and served as governor of Samarkand under Ali ibn Isa ibn Mahan, the governor of Khurasan.
Ali's ruthless exploitation of the province and oppressive fiscal measures caused much resentment among the local elites. Consequently, when in 806 Rafi launched a revolt in Samarkand, it spread quickly across Khurasan, finding support both among the Arabs and the Iranian natives. Rafi also secured the support of the Oghuz and Karluk Turks.
The Caliph Harun al-Rashid dismissed Ali and replaced him with Harthama ibn A'yan, and in 808 marched himself east to deal with the situation, but died in March 809 while at Tus. After Harun's death, Rafi chose to surrender himself to Harun's son and new governor of Khurasan, al-Ma'mun. He was pardoned, and nothing more is known of him after.