Jamāl al-Dīn Abū al-Ḥajjāj Yūsuf ibn al-Zakī ʻAbd al-Raḥmān ibn Yūsuf ibn ʻAbd al-Malik ibn Yūsuf al-Kalbī al-Quḍā’ī al-Mizzī, (Arabic: يوسف بن عبد الرحمن المزي), also called Al-Ḥāfiẓ Abī al-Ḥajjāj, was a Syrian muhaddith and the foremost `Ilm al-rijāl Islamic scholar.

Al-Mizzī was born near Aleppo in 1256 under the reign of the last Ayyubid emir An-Nasir Yusuf. From 1260 the region was ruled by the na'ib al-saltana (viceroys) of the Mamluk Sultanate. In childhood he moved with his family to the village of al-Mizza outside Damascus, where he was educated in Qur’ān and fiqh. ^[3] In his twenties he began his studies to become a muḥaddith and learned from the masters. His fellow pupil and life-long friend was Taqī al-Dīn ibn Taymiyya. It was also Taymiyya’s ideological influence, which although contrary to his own Shāfi’ī legalist inclination, that led to a stint in jail.

Despite his affiliation with Ibn Taymiyya he became head of the Dār al-Ḥadīth al-Ashrafiyya, a leading ḥadīth academy in Damascus, in 1319. And although he professed the Ash’arī doctrine suspicion continued about his true beliefs.^[3] He travelled across the Mamluk Sultanate of Egypt, Syria (الشَّام), and Ḥijāz and became the greatest `Ilm al-rijāl (عِلْمُ الرِّجال) scholar of the Muslim world and an expert grammarian and philologist of Arabic.^[3] He died at Dar al-Hadith al-Ashrafiyyah in Damascus in 1341/2 and was buried in the Sufiyyah graveyard.^[7]

• Al-Dhahabī
• ‘Abd al-Wahhab al-Subkī
• Ismā‘īl ibn Kathīr  – Ibn Kathir married a daughter of al-Mizzī.^[8]
• Ibn al-Furat^[9]
• Najm ad-Din al-Tufi

• Tahdhīb al-kamāl fī asmā’ al-rijāl; biographical lexicon and comprehensive reworking of Al-Kamal fi Asma' al-Rijal, a collection of narrator biographies^[7] of the transmitters of isnāds in the Six major Hadith collections and others, based upon the tarf (beginning segment) of the hadith.^[7] The Tahdhīb includes Ruwāt kuttub al-sitta. Al-Asqalānī and others wrote compendia of this work.^[3]
• Tuḥfat al-ashraf bi-Ma’rifat al-Aṭraf; alphabetically indexed encyclopaedia of the musnads of the first generation transmitters, the Companions of the Prophet. An indispensable resource for the study of Muslim tradition that comprises al-Nasā’ī's Al-Sunan al-kubrā.^[3]