- Jiří, z Poděbrad, King of Bohemia, 1420-14711
- John I, King of Portugal, 1357-14332
- John II, King of Aragon, 1397-14791
- John II, King of Portugal, 1455-14951
- John IV, King of Portugal, 1604-16561
- John Manuel, Prince of Portugal, 1537-15541
- John V, King of Portugal, 1689-17501
- John, Duke of Burgundy, 1371-14191
- John, the Apostle, Saint1
- Joseph (Son of Jacob)1
- Juan II, King of Castile and Leon, 1405-14541
- Juana, la Loca, Queen of Castile, 1479-15551
- Juana, of Austria, Princess of Portugal, 1535-15732
- Juana, of Austria, Princess of Portugal, 1535-1573--Correspondence1
- Judaism6
- Judaism--Customs and practices2
- Judaism--Doctrines1
- Judaism--Liturgy1
- Judeo-Arabic language2
- Judeo-Arabic letters1