I-L
- Iggulden, Hal & Conn
- Ignatius, Fr. of the Side of Jesus, Passionist
- Ignatz, Marie
- Ince, Elizabeth M.
- Irenaeus, St. of Lyons
- Jarrett, Very Rev. Bede, O.P., M.A., S.T.L.
- Jesuit Fathers of St. Mary's
- John of Damascus, St.
- Johnson , Rev. George, Ph.D.
- Jone, Rev. Heribert
- Kalinowski, E. J.
- Kolbe, St. Maximilian Maria
- Kalpakgian, Dr. Mitchell
- Kalvelage, Br. Francis M., FI
- Kane, Fr. John A.
- Keane, Gerard J.
- Kelly, Fr. Gerald
- Kempis, Thomas a
- Keyes, Frances Parkinson
- Kirkwood, Mr. R. Cort
- Knecht, Bishop Frederick Justus, D.D.
- Kurth, Godfrey
- Landroit, Monseigneur
- Lang, U. M.
- Lanz, Tobias J.
- Lapide, Cornelius a
- Larnen, Brendan, O.P.
- Lasance, Fr. F. X.
- Laux, Fr. John, M.A.
- Laveille S.J., Fr. E.,
- Lavin, Dr. Paul
- Lavin, Robert
- Lawler, Phillip F.
- Lee, G., C.S.Sp.
- Lee, Hannah Sawyer
- Lefebvre, Archbishop Marcel
- Lehodey, Rt. Rev. Dom Vitalis
- Lenz, Rev. John M.
- Leo XIII, Pope
- Libietis, Father Helmuts
- Liguori, St. Alphonsus De
- Little, Vima G.
- Loidi, J. Urtreaga
- Lomask, Milton
- Louis Marie de Montfort, Saint
- Louis, Venerable of Granada
- Lovasik, Lawrence G. , S.V.D.
- Lucia, Sr.