135 authors whose works are free to read in full in Nicaea Library, from Clement of Rome and Augustine to Aquinas, Luther, Calvin, Teresa of Ávila and Newman.
- Adolf von Harnack — 7 works
- Adomnán of Iona — 1 work
- Albert the Great — 1 work
- Alessandro Manzoni — 1 work
- Alfred Edersheim — 1 work
- Alonso Rodríguez — 5 works
- Alphonsus Liguori — 7 works
- Ambrose of Milan — 2 works
- Anselm of Canterbury — 1 work
- Anthony of Padua — 1 work
- Aristotle — 4 works
- Athanasius of Alexandria — 2 works
- Augustine of Hippo — 12 works
- Basil of Caesarea — 4 works
- Bede — 2 works
- Benedict of Nursia — 2 works
- Bernard of Clairvaux — 3 works
- Blaise Pascal — 1 work
- Boethius — 3 works
- Bonaventure — 2 works
- Boniface — 1 work
- Bridget of Sweden — 1 work
- Brooke Foss Westcott — 1 work
- Brother Lawrence of the Resurrection — 1 work
- Catherine of Genoa — 1 work
- Catherine of Siena — 3 works
- Charles Haddon Spurgeon — 3 works
- Charles Hodge — 3 works
- Count Lützow — 2 works
- Cyril of Alexandria — 5 works
- Dante Alighieri — 4 works
- David Hume — 1 work
- David S. Schaff — 2 works
- Dionysius the Areopagite — 1 work
- Egeria — 1 work
- Ephrem the Syrian — 1 work
- Epictetus — 1 work
- Eusebius of Caesarea — 5 works
- Evagrius Scholasticus — 1 work
- Flavius Josephus — 2 works
- Francis de Sales — 3 works
- Francis of Assisi — 1 work
- Francisco de Vitoria — 3 works
- François Fénelon — 1 work
- Fray Bartolomé de las Casas — 5 works
- Fray Luis de León — 3 works
- Fyodor Dostoevsky — 1 work
- G. K. Chesterton — 3 works
- George Borrow — 4 works
- George Herbert — 1 work
- George Park Fisher — 1 work
- Gertrude the Great — 1 work
- Gregory of Nyssa — 1 work
- Gregory of Tours — 1 work
- Gregory the Great — 5 works
- Heinrich Bullinger — 3 works
- Henry Barclay Swete — 1 work
- Henry Melvill Gwatkin — 1 work
- Henry Suso — 1 work
- Huldrych Zwingli — 3 works
- Ignatius of Loyola — 3 works
- Irenaeus of Lyons — 1 work
- Isaac the Syrian — 1 work
- J. C. Ryle — 1 work
- J. F. Bethune-Baker — 1 work
- Jacobus Arminius — 3 works
- Jaime Balmes — 6 works
- Jan Hus — 2 works
- Jane Frances de Chantal — 1 work
- Jean-Pierre de Caussade — 1 work
- Jeremy Taylor — 2 works
- Jerome — 1 work
- John Bunyan — 1 work
- John Calvin — 51 works
- John Chrysostom — 7 works
- John Donne — 1 work
- John Foxe — 1 work
- John Henry Newman — 12 works
- John Locke — 1 work
- John Milton — 2 works
- John of Damascus — 2 works
- John of Kronstadt — 1 work
- John of the Cross — 5 works
- John Owen — 1 work
- John Tauler — 1 work
- John Wesley — 1 work
- John Wycliffe — 1 work
- Jonathan Edwards — 2 works
- Joseph Butler — 1 work
- Juan Donoso Cortés — 1 work
- Juan Eusebio Nieremberg — 1 work
- Julian of Norwich — 1 work
- Karl Joseph von Hefele — 5 works
- Lorenzo Scupoli — 2 works
- Louis Duchesne — 4 works
- Louis of Granada — 4 works
- Louis-Marie Grignion de Montfort — 1 work
- Macarius the Egyptian — 1 work
- Marcus Aurelius — 1 work
- Marcus Tullius Cicero — 1 work
- Martin Luther — 7 works
- Matthew George Easton — 1 work
- Matthew Henry — 6 works
- Menno Simons — 1 work
- Nicholas of Cusa — 1 work
- Origen — 1 work
- Otto Bardenhewer — 1 work
- Palladius of Galatia — 1 work
- Patrick of Ireland — 1 work
- Pedro Calderón de la Barca — 1 work
- Pedro de Ribadeneira — 1 work
- Peter Abelard — 1 work
- Peter of Alcántara — 1 work
- Philip Melanchthon — 2 works
- Philip Schaff — 9 works
- Philo of Alexandria — 4 works
- Plato — 11 works
- Plotinus — 4 works
- R. H. Charles — 2 works
- Reinhold Seeberg — 2 works
- René Descartes — 1 work
- Richard Hooker — 2 works
- Richard Rolle — 1 work
- Robert Bellarmine — 3 works
- San Juan Clímaco — 1 work
- San Juan de Ávila — 1 work
- Teresa of Ávila — 6 works
- Tertullian — 1 work
- Thomas Aquinas — 11 works
- Thomas More — 1 work
- Thomas à Kempis — 2 works
- Walter Hilton — 1 work
- William Langland — 1 work
- William Law — 1 work
- William Paley — 2 works