Author
- Jacopo Ragone1
- Jacques Millet1
- Joannes Thomas Beltamino1
- Joham de Vernoils1
- Johannes Lichtenberger1
- Johannes de Sacrobosco1
- John Felton1
- John II of Castile1
- John XXI1
- John of Lancaster, 1st Duke of Bedford1
- John, Duke of Berry1
- Joseph ben Moses Sarfati1
- Josephus1
- Juan de Torquemada1
- Juana I of Castile1
- Jullien Gervais1
- Kingdom of England1
- Kingdom of Naples1
- Laurentius Cynthius1
- Leo I1