- Joannes de Caligariis1
- John VIII Palaeologus, Emperor of the East, 1392-14481
- Judaism--Controversial literature1
- Judas Iscariot1
- Judgment Day1
- János I Zápolya, King of Hungary, 1487-15401
- Kingdom of God1
- Kirchmair, Georg, 1481-15541
- Knowledge, Theory of1
- Kölner Dom1
- Labyrinths1
- Lamberto, Jacopo di1
- Lamucci, Corso1
- Lanaiolo, Gherardo1
- Land titles--Registration and transfer1
- Language and languages--Philosophy1
- Laterino, Cristoforo1
- Laterino, Pietro1
- Lathom, Robert de, 13th century1
- Latin drama (Comedy)1