Author
- Ibrāhīm al-Ḥalabī1
- Innocent III1
- Isidore of Seville1
- Ismail ibn Hammad al-Jawhari1
- Ismāʻīl ibn Abī Bakr Ibn al-Muqrī1
- Izz al-Din ibn Hibatullah ibn Abi l-Hadid1
- Ja'far Kashfi1
- Jacobus de Cessolis1
- Jacobus de Voragine1
- Jacques Legrand1
- Jalal al-Din Davani1
- Jalaluddin al-Mahalli1
- Jean de Meun1
- Johannes Gherinx1
- John Cassian1
- John Lydgate1
- John of Glastonbury1
- John of Howden1
- Juan Antonio de Hozes Sarmiento1
- Juan Ortiz Campoy1