Author
- Johann Herolt2
- Johann Neudörffer the Younger2
- Johannes Nider2
- John Burgh2
- John Felton2
- John Halgren of Abbeville2
- John Wycliffe2
- John XXII2
- John of Garland2
- John of Genoa2
- Jordan von Quedlinburg2
- Josef ibn Tabul2
- Joshua Benzion Segre2
- Judah Leib Pukhovitser2
- Judah Rosanes2
- Judah ben Saul ibn Tibbon2
- Julian of Toledo2
- Julianus Pomerius2
- Justin2
- Jérôme Lalande2