Author
- Isaac Israeli ben Joseph1
- Isaac Israeli ben Solomon1
- Isidore of Seville1
- Ismail ibn Hammad al-Jawhari1
- Ivo of Chartres1
- Jacques Millet1
- Jaghmini1
- Jawād ibn Saʻd Jawād al-Baghdādī1
- Jean Bayard1
- Jean Marot1
- Jean Passerat1
- Johannes Appenzeller1
- Johannes Lichtenberger1
- Johannes Schöner1
- John Burgh1
- John Chrysostom1
- John Dominici1
- John Felton1
- John XXI1
- John Dokeianos1