- Isidore, of Seville, Saint, -6361
- Islam1
- Islamic cosmology1
- Islamic law1
- Islamic philosophy1
- Italy--Sicily1
- James, the Greater, Saint1
- Jerónima de la Asunción, madre, 1555-16301
- Jesuit drama, Spanish1
- Jewish funeral rites and ceremonies1
- Jewish law1
- Jewish mourning customs1
- Jewish religious poetry, Ladino1
- Jews--Medicine1
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- Jiménez de Cisneros, Francisco, 1436?-15171
- John II, King of Aragon, 1397-14791
- John the Baptist's Day1
- Juana, la Loca, Queen of Castile, 1479-15551
- Juana, of Austria, Princess of Portugal, 1535-15731