- John IV, King of Portugal, 1604-16561
- John Manuel, Prince of Portugal, 1537-15541
- John V, King of Portugal, 1689-17501
- Juana, of Austria, Princess of Portugal, 1535-15731
- Kings and rulers1
- Lafões, Pedro Henrique de Bragança, Duque de, 1718-17611
- Law1
- Lippomano, Luigi, 1500-15591
- Manuel I, King of Portugal, 1469-15211
- Manuscripts, English (Middle)1
- Manuscripts, German1
- Manuscripts, Medieval1
- Manuscripts, Portuguese1
- Manuscripts, Turkish1
- Maria Anna Josefa, Queen, consort of John V, King of Portugal, 1683-17541
- Marriage (Canon law)1
- Marriage (Canon law)--Dispensations1
- Marshals1
- Massachusetts--Boston1
- Maximilian I, Holy Roman Emperor, 1459-15191