Author
- Jacopo Piccolomini-Ammannati1
- Jacques de Vitry1
- Jean Germain1
- Jean Gerson1
- Jean de Lignieres1
- Jean de Roquetaillade1
- Johann Herolt1
- Johannes Leonis1
- Johannes Milis1
- John Burgh1
- John Capgrave1
- John Chrysostom1
- John Gower1
- John Mandeville1
- John XXII1
- John of Genoa1
- John of Seville ?1
- Jordan von Quedlinburg1
- Kingdom of Naples1
- Leo I1