- 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 Baptist's Day1
- John, Duke of Burgundy, 1371-14191
- John, King of England, 1167-12161
- John, of Damascus, Saint1
- John, of Daylam1
- John, the Apostle, Saint4
- John, the Baptist, Saint2
- Jonah (Biblical prophet)1
- Joseph (Son of Jacob)8
- Joseph (Son of Jacob) in the Qurʼan2
- Joseph Della Reina, active 15th century2
- Juan II, King of Castile and Leon, 1405-14541
- Juana, la Loca, Queen of Castile, 1479-15552
- Juana, of Austria, Princess of Portugal, 1535-15732
- Juana, of Austria, Princess of Portugal, 1535-1573--Correspondence1
- Judaism87
- Judaism (Christian theology)1