While this fairytale doesn't really have gruesome origins, I thought I would share it anyway. Goldilocks and the Three Bears is a 19th century British fairytale. The later variations are all based on the initial fairytale.
Version 1 By Robert Southey
In Robert Southey's version of the tale, three anthropomorphic bears – "a little, small, wee bear, a middle-sized bear, and a great, huge bear" – live together in a house in the woods. Southey describes them as very good-natured, trusting, harmless, tidy, and hospitable. Each of these "bachelor" bears has his own porridge bowl, chair, and bed. One day they make porridge for breakfast, but it is too hot to eat, so they decide to take a walk in the woods while their porridge cools. An old woman approaches the bears' house. She has been sent out by her family because she is a disgrace to them. She is impudent, bad, foul-mouthed, ugly, dirty, and a vagrant deserving of a stint in the House of Correction. She looks through a window, peeps through the keyhole, and lifts the latch. Assured that no one is home, she walks in. The old woman eats the Wee Bear's porridge, then settles into his chair and breaks it. Prowling about, she finds the bears' beds and falls asleep in Wee Bear's bed. The end of the tale is reached when the bears return. Wee Bear finds his empty bowl, his broken chair, and the old woman sleeping in his bed and cries, "Somebody has been lying in my bed, and here she is!" The old woman wakes, jumps out the window and is never seen again.
Twelve years after the publication of Southey's tale, Joseph Cundall transformed the antagonist from an ugly old woman to a pretty little girl in his Treasury of Pleasure Books for Young Children. He explained his reasons for doing so in a dedicatory letter to his children, dated November 1849, which was inserted at the beginning of the book:
The "Story of the Three Bears" is a very old Nursery Tale, but it was never so well told as by the great poet Southey, whose version I have (with permission) given you, only I have made the intruder a little girl instead of an old woman. This I did because I found that the tale is better known with Silver-Hair, and because there are so many other stories of old women.