Author
- Isaac Israeli ben Joseph1
- Ishmael ben Abraham Isaac ha-Kohen1
- Jacob ben David ben Yom Tov1
- Jacob ben Hayyim Zemah1
- Jacobus de Cessolis1
- Jacopo Ragone1
- Jacques de Vitry1
- Jehiel ben Jekuthiel ben Benjamin Anav1
- Jerome1
- Jewish Community of Pitigliano, Italy1
- John XXI1
- John XXII1
- John de Breton1
- John de Seccheville1
- Joseph Trani1
- Joseph ben Abraham Gikatilla1
- Joseph ben Ephraim Karo1
- Josephus1
- Julianus Pomerius1
- Justin1