Encyclopedias, Almanacs, Transcripts, and Maps
- Irish Free State/Republic, relations with
- Irish Immigration
- Irish Nationalist Movement Since 1800
- Irish rebellions
- Iron Hill, Delaware
- Iron Mining and Metallurgy
- Iroquois Confederation
- Iroquois League
- Irvine agreement
- Irvine, James
- Irvine, William
- Isaac ben Judah Abravanel
- Isaac M. Singer
- Isaac McCoy
- Isaac Pinto
- Isaac Theophilus Akunna Wallace-Johnson
- Isabel Clara Eugenia and Albert of Habsburg (Isabel Clara Eugenia, 1566–1633; Albert of Habsburg, 1559–1621)
- Isabel Martinez de Perón
- Isabella Karle
- Isaiah Berlin