Author
- Innocent V1
- Isaac Alfasi1
- Isaac ben Joseph of Corbeil1
- Ismail al-Isfahani1
- Izz al-Din ibn Hibatullah ibn Abi l-Hadid1
- Jacob HaLevi of Marvège1
- Jacobus de Burgo1
- Jacopone da Todi1
- Jalal al-Din al-Qazwini1
- Jalaluddin al-Mahalli1
- James of Lausanne1
- James of Viterbo1
- Jamāl al-Dīn Aḥmad ibn Muḥammad Ẓāhirī1
- Jamāl al-Dīn Ḥaṣīrī1
- Jean de Lignieres1
- Jean de Meun1
- Johannes von Freiburg1
- John Cassian1
- John Gower1
- John Halgren of Abbeville1