- Jiménez de Cisneros, Francisco, 1436?-15171
- Joachim, Saint1
- John I, King of Portugal, 1357-14331
- John II, King of Aragon, 1397-14791
- John IV, King of Portugal, 1604-16561
- John Manuel, Prince of Portugal, 1537-15541
- John V, King of Portugal, 1689-17501
- John VIII Palaeologus, Emperor of the East, 1392-14481
- Judaism--Ari rite1
- Judaism--Customs and practices1
- Judaism--Prayers and devotions1
- Judeo-Arabic language1
- Judeo-Persian language1
- Judicial process (Islamic law)1
- Jurjānī, ʻAlī ibn Muḥammad, al-Sayyid al-Sharīf, 1340-1413. Sharḥ mushkilāt al-Kashshāf1
- Jurjānī, ʻAlī ibn Muḥammad, al-Sayyid al-Sharīf, 1340-1413. Ḥāshiyah ʻalá Sharḥ Ḥikmat al-ʻayn1
- Jurjānī, ʻAlī ibn Muḥammad, al-Sayyid al-Sharīf, 1340-1413. ḥāshiyah ʻalá Sharḥ Mukhtaṣar al-Muntahá1
- Jārabardī, Aḥmad ibn al-ḥusayn, d. 1346. Sharḥ al-Shāfiyah1
- Kalāʼī, Muḥammad ibn Sharaf, d. 13751
- Karaites1