Former Owner
- Julius Hess1
- Katherine Petersen1
- Kenneth Hyde1
- Lajos Graf Apponyi de Nagy-Appony1
- Lancino Curti1
- Lathrop C. Harper, Inc.1
- Lathrop Colgate Harper6
- Laura Hurd Motion1
- Lawrence J. Schoenberg4
- Leo Olschki5
- Leo S. Olschki Editore6
- Leonardo Bruni1
- Leonardo Lapiccirella2
- Leonardus Martinotius1
- Leonello d'Este, Marquis of Ferrara3
- Leonhardus Cuntius1
- Leopold Gruber1
- Libri, Edoardo, active 20th century1
- Llewelyn Lloyd-Mostyn, 3rd Baron Mostyn of Mostyn1
- Lodovicus Saltariellus1