- John IV, King of Portugal, 1604-16561
- John Manuel, Prince of Portugal, 1537-15541
- John V, King of Portugal, 1689-17501
- John VIII Palaeologus, Emperor of the East, 1392-14481
- John, the Apostle, Saint1
- Juana, of Austria, Princess of Portugal, 1535-15731
- Judaism--Controversial literature1
- Judas Iscariot1
- Judgment Day1
- Julius III, Pope, 1487-15551
- Kapitalbünde1
- Kirchmair, Georg, 1481-15541
- Kölner Dom1
- Lafões, Pedro Henrique de Bragança, Duque de, 1718-17611
- Land grants1
- Land titles--Registration and transfer1
- Latin drama (Tragedy)1
- Latin essays1
- Latin language, Medieval and modern--Grammar1
- Latin language, Medieval and modern--Study and teaching1