Ida of Herzfeld, widow and foundress
Idesbald, Cistercian Abbot of Ten Duinen
Iduberga (Itta, Ida) of Schelde, Wife of Pepin of Landen the Elder
Ieron (Ion), of Friesland, Priest, martyred by the Northmen
(Clemente) Ignacio Delgado Cebrian, Spanish Dominican Priest, Martyred in Vietnam
Ignacy KIopotowski, Priest, Founder of the Sisters of the Blessed Virgin Mary of Loreto
Ignatius Brianchininov, Russian monk from Vologda
Ignatius Laconi, Capuchin Priest
Ignatius Loyola, Founder of the Society of Jesus, Jesuits
Ignatius of Antioch, Bishop, Martyr, and Apostolic Father
Ignatius of Santhia, Capuchin Priest, who worked in Turin
Ignatius Shoukrallah Maloyan, Armenian Catholic Archbishop of Mardin, Martyr
Ignatius, Patriarch of Constantinople
Igor II, Prince of Kiev
Ildefonso Schuster, Cardinal Archbishop of Milan
Ildefonsus, Bishop of Toledo
Ildemarca (Hilda), Abbess of Fecamp
Illidius of Arvernia, Fourth Bishop of Clermont
Illuminata of Ravenna, Virgin
Illuminatus, Confessor
Imelda Lambertini, Dominican Nun
Ingenuinus, Bishop of Seben (Tyrol)
Innocent, Bishop martyred in Rome
Innocentia, Virgin and Martyr
Ippolito (Hippolytus) Galantini, Lay Man, Founder of the Italian Doctrinaires
Irenaeus of Lyons, Bishop, Martyr, and Father of the Church
Irenarchus of Sebaste, Martyr
Irene of Mount Cornillon, Norbertine Canoness
Irene of Rome, friend and healer of St. Sebastian
Irene of Tancor, Virgin, Martyred in Thessaloniki
Irene, Virgin and Martyr
Irmengard, Abbess of Chiemsee
Irmina, Abbess of Oeren
Isaac of Dalmatia, Abbot of the oldest monastery in Constantinnople, Patron of the Cathedral of St. Petersburg, Russia
Isaac, Abbot of Monteluco, near Spoleto
Isaac, Bishop of Armenia
Isaac, Martyr
Isaac, Syrian Bishop of Nineveh
Isabel (Elizabeth), Queen of Portugal
Isabelle of France, Sister of St. Louis, Poor Clare Abbess
Isaiah, Second Bishop of Rostov
Isidore of Chios, Soldier and Martyr
Isidore of St. Joseph (de Loor), Passionist lay brother
Isidore, Bishop of Seville and Father of the Church
Isidore, Farmer
Ismidon, Bishop of Die
Israel of Dorat, Augustinian Priest, confessor
Ita of Killeedy, Irish Abbess, “foster mother of the saints of Ireland
Ithamar, First Saxon Bishop of Rochester, England
Iuliu Hossu, Romanian Cardinal, Bishop of Cluj-Gheria
Ives (Yves, Ivo, Yvo) Helory, of Kermartin, Brittany, Lawyer and Priest
Ivo, Bishop of Chartres