- Job (Biblical figure)1
- John I, King of Portugal, 1357-14331
- John VIII Palaeologus, Emperor of the East, 1392-14481
- John, Duke of Burgundy, 1371-14191
- John, King of England, 1167-12161
- John, the Baptist, Saint1
- Joseph (Son of Jacob) in the Qurʼan1
- Judaism--Apologetic works1
- Judaism--Functionaries1
- Judaism--Roman rite1
- Judaism--Roman rite--Liturgy1
- Judaism--Sephardic rite--Liturgy1
- Judas Iscariot1
- Judeo-Arabic letters1
- Judeo-Italian language1
- Julian, of Eclanum, Bishop, 380-approximately 4551
- Julii family1
- Julius III, Pope, 1487-15551
- Jurisprudence1
- Jurjānī, ʻAlī ibn Muḥammad, al-Sayyid al-Sharīf, 1340-14131