Former Owner
- John Morgan1
- John Ruskin1
- John Topham1
- John Trotter Brockett1
- John West, 1st Earl De La Warr1
- John Wright1
- Joseph E. Widener7
- Joseph François René de Kergariou1
- Joseph Jekyll1
- Joseph Marie Sormani1
- Joseph Whitney1
- Josephine Widener Wichfield1
- Julia Burgess4
- Julie de Busnel1
- Justin MacCarthy Reagh1
- Karen L. Gould12
- Keith Jarvis3
- Lady Margaret Ayloffe1
- Lambertus Eerens1
- Latham family1