- Agustín, Antonio, 1517-1586. Dialogos de medallas inscriciones y otras antiguedades1
- Alba, Fernando Alvarez de Toledo, duque de, 1507-15821
- Albigenses1
- Alchemy1
- Alchemy--Manuscripts1
- Alfonso I King of Asturias, 693-7561
- Alfonso III, King of Asturias and Leon, approximately 848-approximately 9101
- Alfonso V, King of Asturias and León, 994-1027 or 10281
- Alfonso VI, King of Castile and Leon, 1030-11091
- Alfonso VII, The Emperor, King of Castile, 1104-11571
- Alfonso VIII, King of Castile, 1155-12141
- Alfonso X, King of Castile and Leon, 1221-12842
- Aljamía1
- Amelius, Martyr1
- Amicus, Martyr1
- Ana, Queen, consort of Philip II, King of Spain, 1549-15802
- Anaya, Pedro1
- Annals and chronicles2
- Annotations4
- Anthony, of Padua, Saint, 1195-12311