Former Owner
- John Caryll1
- John D. McKenna1
- John F. Fleming1
- John Harrison-Broadley1
- John Harvey Treat1
- John Ruskin1
- John Shelton Lawrence1
- John Trotter Brockett1
- Joseph François René de Kergariou1
- Joseph Pope1
- Joseph Whitney1
- Joseph-Félix Allard1
- Julius Hess1
- Justin MacCarthy Reagh1
- K. B. Starkie1
- Klaus Dieter Dahmen1
- Kloster Kuringen1
- Kulturhistorisches Museum Magdeburg1
- Latham family1
- Laurence Kirby1