In the actual fairy tale, the little mermaid is first allowed to visit the surface when she turns 15 – and there's some very particular decor she has to wear when she does:
How's she gonna catch a prince in that getup?
Oh, and about that ending. Basically what happens in the book is the prince marries someone else and the little mermaid turns into foam and then some kind of air-being:
Possibly the worst consolation prize in history.
In the actual fairy tale, Snow White is often referred to as a "child" for a lot of the story. In fact, she isn't even a teenager when the Queen first asks her iconic question:
Speaking of the Evil Queen, in the Disney film she of course meets her demise by falling off a cliff. However, in the actual fairy tale the Queen shows up to Snow White's wedding before meeting a slightly more intense end:
In the actual fairy tale, Cinderella has not one, but three different gowns (which she receives from a tree and some birds, not a "fairy god mother.") Also, it turns out those famous slippers aren't even made of glass:
"I love gooooooold."
In the actual fairy tale the stepsisters attempt to make Cinderella's slipper fit by cutting off a toe and a heel (respectively). And on top of that, they make the mistake of attending her wedding:
♫ Blinded by the light, er, pigeons? ♫
In the actual fairy tale Maleficent is just another one of the fairies (which, BTW there are 13 of). Also, they're not even fairies, but "wise women" – and thanks to the King's weird policies Maleficent gets totally screwed over:
Still, she can obviously rock a cloak and dress in any color.
In the actual fairy taleFrozen is super loosely based on, there is no Elsa. However, there is a little boy named Kay and just like Elsa he has a sister (OK technically, a friend, but practically a sister) who goes on a crazy journey to find him: