Author
- Isidore of Seville1
- Jacob Saphir1
- Jacopo Piccolomini-Ammannati1
- Jacopone da Todi1
- Jacques de Vitry1
- James of Milan1
- Jean-François Roussin1
- Jewish Community of Padua, Italy1
- Jewish Community of Pitigliano, Italy1
- Jewish community of unidentified city, Italy1
- Joan Martines1
- Joannes Dominicus de Marchis1
- Joannes Oliva1
- John Wycliffe1
- John XXII1
- John de Breton1
- John de Seccheville1
- Julius II1
- Julius III1
- Leo III1