Ṭāhir ibn Ḥusayn (, "Tâhereben Hoseyn"; , "Tahir bin al-Husayn"), also known as Dhul-Yamīnayn (, "the ambidextrous"), and al-Aʿwar (, "the one-eyed"), was an Iranian general and governor during the Abbasid caliphate. Specifically, he served under al-Ma'mun during the Fourth Fitna and led the armies that would defeat al-Amin, making al-Ma'mun the "caliph". He was then rewarded as governor of Khorasan, which marked the beginning of the Tahirid dynasty.