Former Owner
- Lady Margaret Ayloffe1
- Lajos Graf Apponyi de Nagy-Appony1
- Lambertus Eerens1
- Lancino Curti1
- Latham family1
- Lathrop C. Harper, Inc.4
- Lathrop Colgate Harper8
- Laura Hurd Motion1
- Laurence Claiborne Witten II4
- Laurence Kirby1
- Laurence William Hodson3
- Laurentius van der Torqel1
- Law Society1
- Lawrence J. Schoenberg29
- Lehn of Denmark1
- Leicester Harmsworth5
- Leo Olschki5
- Leo S. Olschki Editore7
- Leonard Grey, 1st Viscount Grane1
- Leonardo Bruni1