R is for...Royalty!

Fairy tales often include royalty, like princes, princesses, kings or queens. In most fairy tales, either the main character is already a part of the royal family, or they join one by the end of the story.

Taken from here

In The Little Mermaid, the mermaid is originally part of a royal family under the sea, with her father being the Sea-King. She gives up her royal life to marry her true love. In the original version, she leaves a royal family to die, but in the Disney version, she leaves one royal family to join another. Sleeping Beauty and Snow White were also originally princesses who went on to marry princes from a different family.

Taken from here

In Cinderella, she is an ordinary girl who meets a prince and marries into a royal family, becoming a princess. The same thing happens to Belle in Beauty and the Beast. In Rapunzel, she is also an ordinary girl at the beginning of the tale, but when a prince hears her singing they fall in love and she goes with him to his kingdom to be a princess and live happily ever after.
In The Princess and the Pea royalty is very important, as instead of meeting a girl, falling in love and marrying her to make her a princess, the prince is adamant that the girl he marries must be a princess already. This is why he does the 'pea test'.

Taken from here

In Rumpelstiltskin, the main character becomes a queen right at the beginning of the story, which is unusual for fairy tales. Because the King is impressed with the woman's skills at turning straw into gold, he marries her and makes her his queen. Because Rumpelstiltskin helped her with this, he demanded payment in the form of her first born child. He said that if she could guess his name, he needn't hand the child over. One of her messengers learns his name and she therefore gets to keep her child.
Of course, not all fairy tales have royalty in them, but a lot of well known ones do. :)