Author
- Ibn ʿAqīl1
- Imam Ar-Rafi'i1
- Innocent III1
- Isaac Alfasi1
- Isaac ben Joseph of Corbeil1
- Ismail al-Isfahani1
- Izz al-Din ibn Hibatullah ibn Abi l-Hadid1
- Jacob ben Asher1
- Jacobus de Cessolis1
- Jacopo Piccolomini-Ammannati1
- Jacques Lempereur1
- Jalaluddin al-Mahalli1
- Jamāl al-Dīn Aḥmad ibn Muḥammad Ẓāhirī1
- Jamāl al-Dīn Ḥaṣīrī1
- Jean de Lignieres1
- John Gower1
- John Larry England1
- John XXII1
- Joseph ben Abraham Gikatilla1
- Joseph ben Judah ibn Aknin1