- John VIII Palaeologus, Emperor of the East, 1392-14481
- Joseph (Son of Jacob)1
- Juana, la Loca, Queen of Castile, 1479-15551
- Judaism--Ari rite1
- Judaism--Customs and practices1
- Judaism--Prayers and devotions1
- Judeo-Arabic language1
- Judeo-Persian language1
- Judges1
- Judgment Day (Islam)1
- Judicial process (Islamic law)1
- Julius III, Pope, 1487-15551
- Justa, Saint, -approximately 2871
- Justice, Administration of1
- Jābir ibn Ḥayyān1
- Jāmiʻ al-Azhar1
- Jāmiʻ al-Muẓaffarī (Damascus, Syria)1
- Jārabardī, Aḥmad ibn al-ḥusayn, d. 1346. Sharḥ al-Shāfiyah1
- Karaites1
- Karaites--Liturgy1