- Illumination of books and manuscripts, Dutch1
- Illumination of books and manuscripts, English1
- Illumination of books and manuscripts, Mexican1
- Immortality1
- Immortality--Christianity1
- Impediments to marriage1
- India--Cochin1
- India--Goa (State)1
- Inner Light1
- Innocent III, Pope, 1160 or 1161-12161
- Innocent V, Pope, approximately 1224-12761
- Innocent VIII, Pope, 1432-14921
- Insular scripts1
- Introductions1
- Investiture1
- Iran1
- Iraq1
- Isabel, of Coimbra, Queen, consort of Afonso V, King of Portugal, 1432-14551
- Isagoge (Porphyry)1
- Isaiah (Biblical prophet)1