Author
- Isobel Salcedo Larralde1
- Issachar ben Mordecai ibn Susan1
- Izz al-Din ibn 'Abd al-Salam1
- Izz al-Din ibn Hibatullah ibn Abi l-Hadid1
- Jacob Berab1
- Jacob ben Jacob, ha-Kohen, -approximately 12701
- Jaghmini1
- Jayadeva1
- Jayakr̥ṣṇa1
- Jayāditya1
- John Dennis1
- John Fortescue1
- John Sergeant1
- Josef ibn Tabul1
- Joseph ben Abraham Gikatilla1
- Joshua ibn Shuaib1
- José Pellicer1
- Juan López Ossorio1
- Juan Valenzuela Velázquez1
- Juan de Mongaston1