Author
- Innocent III1
- Inquisition Sicily)1
- Iohannes de Ianna1
- Jacobus de Cessolis1
- Jacopone da Todi1
- Jean Germain1
- Joannes Francis Binus1
- Johann Eck1
- Johann Herolt1
- Johannes Mathesius1
- John Chrysostom1
- John Dominici1
- John Herd1
- John of Garland1
- John of Wales1
- Juan Pérez de Cabrera1
- Juan de Garnica1
- Juana I of Castile1
- Julian of Toledo1
- Justinian I1