Author
- Jacob ben Asher1
- Jacob ben David ben Yom Tov1
- Jacob ben Jacob, ha-Kohen, -approximately 12701
- Jacob ben Reuben ibn Zur1
- Jacob ibn Habib1
- Jacobus de Burgo1
- Jacobus de Cessolis1
- Jacobus de Teramo1
- Jacques Legrand1
- Jacques Millet1
- Jagannāthacandra1
- Jai Singh II1
- Jakob Reifmann1
- Jakob Wimpfeling1
- Jalal Al-Din Al-Khabazi1
- Jalal al-Din Mohammad Tabrizi1
- Jalal al-Din al-Qazwini1
- James Raymond Wellsted1
- James of Lausanne1
- James of Milan1