Former Owner
- John Burns1
- John D. Denman1
- John Eliot Hodgkin2
- John Harvey Treat2
- John Ruskin2
- John Towneley1
- John Trotter Brockett1
- Jonathan Peckover1
- Joseph Görres1
- Joseph L. Lilly1
- Justin MacCarthy Reagh1
- Katherine Petersen1
- Konrad von Maurer1
- Kulturhistorisches Museum Magdeburg1
- Lajos Graf Apponyi de Nagy-Appony1
- Latham family1
- Leo Olschki1
- Louis César de La Baume Le Blanc1
- Louis Jean Gaignat1
- Lucien Delamarre1