- Hypothesis1
- Illegible markings1
- Illegitimacy1
- Illumination of books and manuscripts, Carolingian1
- Incarnation1
- Incunabula1
- Indulgences1
- Indulgences (Canon law)1
- Inheritance and succession (Islamic law)1
- Initials (Abbreviations)1
- Innocent III, Pope, 1160 or 1161-12161
- Inquisition1
- Insular scripts1
- International relations1
- International trade1
- Ireland1
- Isabel, of Coimbra, Queen, consort of Afonso V, King of Portugal, 1432-14551
- Isaiah (Biblical prophet)1
- Isidore, of Seville, Saint, -6361
- Islamic bindings1