Author
- Alain of Lille1
- Aldobrandino da Siena1
- Alexander V1
- Alfonso X of Castile and Leon1
- Alfonso de Cartagena1
- Alfred of Sareshel1
- Alulphe of Tournai1
- Ambrosiaster1
- Andrew Welch1
- Angelus Callimachus de Monteviridi1
- Anselm of Laon1
- Antonio Millo1
- Arles1
- Armenian Catholic Church1
- Arnaldus de Villa Nova1
- Arnulf of Bohéries1
- Arnulf of Lisieux1
- Arnulf of Orléans1
- Asher ben Jehiel1
- Athanasius of Alexandria1