Catherine of Aragon is famous for being the unfortunate first wife of King Henry VIII. When he was just a royal nobody, Catherine became ill with sweating sickness.
Princess Alexandra Amalie of Bavaria (1826 – 1875) is famous for believing that she swallowed a glass piano as a child. There's even a play about her, The Glass Piano.
We know close to nothing about Helen of Bosnia. Most queens-regnant leave behind almost too much information for us, but Helen left us close to nothing.
Rosamund Clifford (c. 1150 - c. 1176) was Henry II of England's mistress. Unluckily for her, his wife was Eleanor of Aquitaine, who was not at all fond of The Fair Rosamund.
Mary, Queen of Scots, is famous for being executed by her cousin, Queen Elizabeth I. Before her beheading, Mary wrote a letter to her brother-in-law, Henri III.
Sibylle of Cleves was a sister-in-law of Henry VIII who is all but forgotten. She was the eldest daughter, a mother of four Johns, and a brave defender of Wittenberg.
One tends to remember an Empress of Austria more than a Princess of Thurn and Taxis. But Helene in Bavaria led a much happier life away from the imperial throne.
Very few women in history have betrayed their sisters to become the king's mistress. Maybe that's why Marie Anne de Mailly, arguably history's worst sister, is so intriguing.
Marie Antoinette of Austria was the Queen of France who had the bad luck of being consort during the French Revolution. Here is her last letter.
Marozia of Tusculum was the closest thing we had to a female pope. Pope Joan was probably a myth, but we can be sure Marozia existed, since she was related to seven popes.