Author
- Isaak ben Meïr from Düren1
- Ismāʻīl ibn Abī Bakr Ibn al-Muqrī1
- Jacob ben Jacob, ha-Kohen, -approximately 12701
- Jacobus de Cessolis1
- Jacopo Nannis de Piccolomini1
- Jacopo Piccolomini-Ammannati1
- Jean Germain1
- Jean Gerson1
- Jean Le Fèvre de Ressons1
- Jean de Wavrin1
- Jerome1
- Johann Herolt1
- John Burgh1
- John Capgrave1
- John Gower1
- John Mandeville1
- John of Genoa1
- John of Seville ?1
- John, Duke of Berry1
- Jordan von Quedlinburg1