Former Owner
- Mark Lansburgh1
- Mary Augusta Strachey1
- Mary Schell Collins1
- Matteo Barresi1
- Matthew Bloxam1
- Matthew Simpson Parkhurst1
- Matthias Corvinus1
- Maurice Johnson1
- Maximilian Henry of Bavaria1
- Melk Abbey1
- Michael Tomkinson1
- Michaeliskonvent1
- Michel Chasles1
- Michiel family1
- Miguel de Mayora1
- Millard Meiss1
- Milt Freudenheim1
- Moissac Abbey1
- Monasterio de El Paular1
- Morris H. Morgan1