Tahir ibn Husayn (d. 822) was a Persian general and governor during the Abbasid caliphate. Specifically, he served under al-Ma'mun and led the armies that would defeat al-Amin, making al-Ma'mun the caliph.

Afterwards, Tahir was made governor of the eastern Abbasid lands, effectively making him governor of Persia. Tahir later declared independence from the Abbasid empire in 822 by omitting any mention of al-Ma'mun during a Friday sermon. However, he died the same night, and al-Ma'mun appointed Tahir's son to continue at his father's post. This established the Tahirid dynasty, which ruled a semi-autonomous state in eastern Persia.