Former Owner
- Arthur M. Ellis1
- Ashton Lever1
- Audry Wilkens1
- Augustinus de Cagnolis1
- Austin, Jehan1
- Baldasarre Boncompagni1
- Baldassarre Boncompagni6
- Ball Collection2
- Baptist Union Theological Seminary2
- Barbarigo family1
- Barbe de Laon1
- Baron Llangattock1
- Bartolomeo Amici1
- Bartolomeo di Larione Martelli1
- Bateman family1
- Battista di Ser Cicco di Fermo1
- Battle Abbey1
- Beatrice de Fouar1
- Beatus Rhenanus1
- Beinecke Rare Book & Manuscript Library1