- John Manuel, Prince of Portugal, 1537-15541
- John V, King of Portugal, 1689-17501
- John the Baptist's Day1
- John, Duke of Burgundy, 1371-14191
- John, King of England, 1167-12161
- Jonah (Biblical prophet)1
- Joseph (Son of Jacob)1
- Judaism1
- Judaism--Liturgy1
- Jugurthine War (111-105 B.C.)1
- Julian, of Eclanum, Bishop, 380-approximately 4551
- Justinian I, Emperor of the East, 483?-5651
- Karo-Batak dialect1
- Kekchi language1
- Kings and rulers--Duties1
- Knowledge, Theory of1
- Knowledge, Theory of (Religion)1
- Kufic1
- Kufr (Islam)1
- Kyi︠e︡vo-Pechersʹka lavra1