Author
- Hugh of Saint Victor1
- Hugh of Saint-Cher1
- Iacopo Bracciolini1
- Iacopo da Benevento1
- Immanuel Bonfils1
- Innocent III1
- Innocent XI1
- Isaac Israeli ben Joseph1
- Jabir ibn Hayyan1
- Jacob ben Jacob, ha-Kohen, -approximately 12701
- Jacobus de Cessolis1
- Jacobus de Voragine1
- Jacopo Ragone1
- Jean de Roquetaillade1
- Joannes de Crivelli1
- John Dominici1
- John XXI1
- Joseph Angelet1
- Joseph ben Abraham Gikatilla1
- Josephus1