Former Owner
- John West, 1st Earl De La Warr1
- John Willis1
- John Wright2
- John de Vere, 12th Earl of Oxford1
- Joseph Barrois1
- Joseph E. Widener7
- Joseph François René de Kergariou1
- Joseph Jekyll1
- Josephine Widener Wichfield2
- Judith Lady Montefiore College1
- Jules Bonhomme1
- Katholieke Universiteit te Leuven Universiteitsbibliotheek1
- Kenneth Hyde1
- Klaus Dieter Dahmen1
- Konrad von Maurer1
- Kulturhistorisches Museum Magdeburg1
- Lady Margaret Ayloffe1
- Lambach Abbey1
- Lambertus Eerens1
- Lancino Curti1