A royal mistress is the historical position of a mistress to a monarch or an heir apparent. Some mistresses have had considerable power. These powerful mistresses have been commonly referred to as the "power behind the throne". The prevalence of the institution can be attributed to the fact that royal marriages were until recent times conducted solely on the basis of political and dynastic considerations, leaving little space for the monarch's personal preferences in the choice of a mate.
In European history the children of mistresses were not normally included in the line of succession, except perhaps when secret marriages were alleged. Hence the Monmouth Rebellion when James Scott, 1st Duke of Monmouth claimed the thrones of England and Scotland on the grounds that his mother had been the wife, rather than a mistress, of Charles II.
Edith Swanneck, mistress to King Harold II
Rosamund Clifford, mistress to Henry II
Alice Perrers, mistress to Edward III
Jane Shore, mistress to Edward IV
Bessie Blount, mistress to Henry VIII
Mary Boleyn, mistress to Henry VIII
Anne Boleyn, mistress (later queen) to Henry VIII
Margaret Erskine, mistress to James V
Lucy Walter, mistress to Charles II
Barbara Villiers, 1st Duchess of Cleveland, mistress to Charles II
Louise de Kérouaille, Duchess of Portsmouth, mistress to Charles II
Nell Gwynne, mistress to Charles II
Moll Davis, mistress to Charles II
Hortense Mancini, mistress to Charles II
Arabella Churchill, mistress to James II
Catherine Sedley, Countess of Dorchester, mistress to James II
Elizabeth Villiers, mistress to William III
Ehrengard Melusine von der Schulenburg, Duchess of Kendal and Munster, mistress to George I
Henrietta Howard, Countess of Suffolk, mistress to George II
Mary Scott, Countess of Deloraine (1703–44), mistress to George II
Amalie von Wallmoden, Countess of Yarmouth, mistress to George II
Hannah Lightfoot, mistress to George III
Maria Anne Fitzherbert, mistress to George IV
Frances Villiers, Countess of Jersey, mistress to George IV
Grace Elliot, mistress to George IV
Mary Robinson, mistress to George IV
Marchioness of Hertford mistress to George IV
Marchioness Conyngham mistress to George IV
Dorothy Jordan, mistress to Prince William who later became William IV
Sarah Bernhardt mistress to Edward VII
Jennie Jerome, mistress to Edward VII
Lillie Langtry, mistress to Edward VII
Daisy Greville, Countess of Warwick, mistress to Edward VII
Alice Keppel, mistress to Edward VII
Agnes Keyser, mistress to Edward VII
Freda Dudley Ward, mistress to Edward VIII
Lady Furness, mistress to Edward VIII
Wallis Simpson, mistress and later wife to Edward VIII
Camilla Parker-Bowles, mistress and later wife to Charles, Prince of Wales
Anna Mons (Russia)
Anna Lopukhina (Russia)
Caroline Lacroix (Belgium)
Diane de Poitiers (France)
Joséphine de Beauharnais (France)
Hedvig Taube (Sweden)
Katharina Schratt (Austria)
Lola Montez (Bavaria)
Madame de Pompadour (France)
Magda Lupescu (Romania)
Maria Naryshkina (Russia)
Maria Peres de Enxara, mistress to Afonso III of Portugal (Portugal)
Marie, Countess Walewski (France)
Mary Vetsera, Baroness (Austria)
Bianca Cappello (Italy)
Rosa Vercellana (Italy)
Sophie Amalie Moth (Denmark)
Royal mistress Wikipedia (Text) CC BY-SA