- Iago
- Ibarnavarro, Justo
- Ibañez
- Ibeles, Hans
- Ibn al-Awwam, Abu Zakariya Yahya ibn Mohammed
- Ibrahim Clarete → González Bravo, Luis
- Ibrahim Karabatir
- Ibrahim Pascha
- Ibsen, Henrik
- Iconoclast → Bradlaugh, Charles
- Iglesias
- Iglesias Posse, Pablo
- Ignace Edouard Horn → Einhorn, Ignácz
- Ignatios I.
- Ignatius von Loyola
- Ihász, Dániel
- Iliński, Alexander
- Illaire, Ernst Emil
- Im Thurn, Johann Conrad
- Im-Thurn, Eduard
- Imandt
- Imandt, Anna
- Imandt, Carl
- Imandt, Caspar
- Imandt, Fanny
- Imandt, Louis (Ludwig) Emil
- Imandt, Margaretha
- Imandt, Peter
- Imandt, Philipp
- Imandt, Robert
- Imaz, José de
- Imbert, Jacques
- Imhof, Anton Albrecht von
- Impens, J. D.
- Imre Vahot →
- Imrefi
- Inama-Sternegg, Karl Theodor von
- Inca Yupangui, Dionisio
- Ine
- Infantado, Pedro Alcántara Álvarez de Toledo y Salm-Salm, duque del
- Infantado, duques del
- Infante, Facundo
- Ingenohl, Friedrich
- Inglis, Sir John Eardley Wilmot
- Inglis, 2nd Baronet, Sir Robert Harry
- Ingram, John Kells
- Inguanzo, Pedro
- Innozenz IX.
- Innozenz X.
- Innozenz XI.
- Innozenz XII.
- Innozenz XIII.
- Io
- Ioannes Bodinus → Bodin, Jean
- Ioannes VIII. Palaiologos
- Iov
- Iovanovic (Іовановић), Vladimir
- Iphigenie
- Ireland, Alexander
- Ireton, Henry
- Iriarte, Martín José de
- Ironfield
- Irving, Thomas
- Irwin → O'Donovan Rossa , Mary Jane (Molly)
- Irwin, Henry Crossley
- Irányi, Daniel
- Isaak
- Isabel de Portugal
- Isabel de Portugal
- Isabel, Isabella, Isabelle →
- Isabella II.
- Isabel I., la Católica
- Isaev (Исаевъ), Andrej Alekseevič
- Isagoras
- Isard
- Isaschar
- Isecern → Zschackwitz, Johann Ehrenfried
- Isidor
- Isidor von Sevilla
- Iskander → Gercen, Aleksandr Ivanovič
- Ismail Pascha
- Ismail Siddiq
- Ismene
- Isnard, Maximin
- Isokrates
- Isquierdo
- Israel Beer Josaphat (bis 1844) → Reuter, Paul Julius de
- Istúriz, Francisco Javier de
- Iturbe, José Ignacio de
- Ituriaga
- Iturrigaray, José de
- Itzcóatl
- Itzenplitz, Heinrich Friedrich August von
- Itzig → Lassalle, Ferdinand
- Iulia
- Iulianus
- Iulius Caesar, Gaius
- Iulius Caesar (Caligula), Gaius
- Iulius Caesar (Prätor 92 v. Chr.), Gaius
- Iulius Caesar Augustus, Tiberius
- Iulius Caesar Octavianus (ab 27 v. Chr. Augustus), Gaius
- Iulius Paulus
- Iulius Phaedrus, Gaius
- Iulius Solinus, Gaius
- Iunianus Iustinus, Marcus
- Iunius Brutus Caepio, Marcus
- Iunius Iuvenalis, Decimus
- Iunius Moderatus Columella, Lucius
- Iupiter (Jupiter)
- Iustinianus I.
- Iuvenal → Iunius Iuvenalis, Decimus
- Iuvenalis →
- Ivan Osipov → Kain, Van'ka
- Ivan III. Vasil’evič
- Ivan IV. Vasil’evič
- Ivan V.
- Ivan VI.
- Ives, Malcolm
- Ivory, H.
- Ixtlilxóchitl, Fernando de Alva
- Iznardi, Angel
- Izquierdo, Eugenio