Former Owner
- Joseph E. Widener8
- Joseph François René de Kergariou1
- Joseph Jekyll1
- Joseph Whitney1
- Josephine Widener Wichfield2
- José Antonio Conde1
- Juan Burgueño1
- Juan de Londono1
- Juana I of Castile1
- Julian Burgueño1
- Julius Hess1
- Justin MacCarthy Reagh1
- Katherine Petersen1
- King Lawrence Parker1
- Kloster Kuringen1
- Konrad von Maurer1
- Lady Margaret Ayloffe1
- Lajos Graf Apponyi de Nagy-Appony1
- Latham family1
- Lathrop Colgate Harper2