influential Arab historian.

Ibn al-Athīr spent a scholarly life in Mosul, but often visited Baghdad. He was for a time with Saladin's army in Syria and later lived in Aleppo and Damascus. His chief work was a history of the world, al-Kāmil fī at-tārīkh (“The Complete History”), starting with the creation of Adam. Long a standard work, this history has been criticized in the 20th century for being somewhat derivative. He also wrote a history of the atabegs (former Seljuq army officers who founded dynasties) of Mosul called al-Bāhir, which was drawn from his own experience and from that of his father, who held office under the Zangids of Mosul. Among his other works were compilations of biographical and genealogical material of earlier authors.

Ibn al-Athīr's older brother, Majd ad-Dīn ibn al-Athīr (1149–1210), who worked in Mosul for its ruler and was a scholar of note, made a collection of the sayings and acts of the Prophet Muḥammad and a dictionary of obscure terms in Ḥadīth (accounts of Muḥammad and his followers) collections. The youngest brother, Ḍiyāʾ ad-Dīn ibn al-Athīr (1163–1239), was a noted author and literary critic who worked for Saladin and became vizier to Saladin's son, al-Malik al-Afḍal.