Abu'l-Abbas Muhammad ibn Abdallah ibn Tahir (Arabic: محمد بن عبدالله بن طاهر) (824/5 – November 867) was a Tahirid who served the Abbasid Caliphate as governor and chief of police (sahib al-shurta) of Baghdad from 851 until his death, during a particularly troubled period in the city's history, which included its siege during the civil war of 865–866, in which he played a major role. He also served in the 860s as governor of Iraq, Mecca and Medina, and was noted as a scholar, a poet and a patron of artists and scholars.