- John V, King of Portugal, 1689-17501
- John the Baptist's Day1
- John, the Apostle, Saint1
- Juana, of Austria, Princess of Portugal, 1535-15731
- Judaism--Liturgy1
- Judas Iscariot1
- Judges--Selection and appointment1
- Judgment Day1
- Julian, of Eclanum, Bishop, 380-approximately 4551
- Julii family1
- Justice, Administration of1
- Justinian I, Emperor of the East, 483?-5651
- Kings and rulers--Genealogy1
- Knowledge, Theory of1
- Knowledge, Theory of (Religion)1
- Lafões, Pedro Henrique de Bragança, Duque de, 1718-17611
- Lancelot (Legendary character)1
- Land grants1
- Land titles--Registration and transfer1
- Landowners1