Wikipedia
Nafs-e-Zakiyyah (Pure soul)
According to Shia sources Nafs-e-Zakiyyah (pure soul) is one of the apocalyptic characters that Muhammad al-Mahdi, an ultimate savior of humankind and the final Imam of the Twelve Imams, will send as his envoy to Mecca before his reappearance. He will be killed in Mecca and his death is one of the signs of Muhammad al-Mahdi's reappearance.