Author
- Ildibrandinus1
- Innocent III1
- Jacopo Nannis de Piccolomini1
- Jacques de Vitry1
- Jean Germain1
- Jean-François Roussin1
- John Burgh1
- John Capgrave1
- John Gower1
- John Tiptoft, 1st Earl of Worcester1
- João Freire1
- Julian of Toledo1
- Julianus Pomerius1
- Justinian I1
- Juvenal1
- Kingdom of England1
- Kingdom of Naples1
- Lactantius1
- Leo X1
- Leon Battista Alberti1