In some stories, it could be the result of a curse. Maybe the person has done something immoral or broken an important taboo in their society or a sacred place. The curse then takes effect and changes them into a cock as a form of divine or karmic punishment.
No, there isn't really a famous person with such a transformation story in mainstream literature or well - known tales. Most of these types of stories are fictional creations that are more in the realm of folktales or made - up fantasy stories.
Once upon a time, there was a wizard who was angry with a young man. As a punishment, he cast a spell on the man. Suddenly, the man started to feel strange. His body began to shrink and feathers started to grow all over him. His arms turned into wings and his nose became a beak. Before long, he was completely transformed into a cock. He could only crow and peck at the ground now, living a life very different from before.
One possible story could be in a magical world. There was a young man named Tom who offended a powerful wizard. As a punishment, the wizard cast a spell on him. Tom suddenly felt a strange tingle all over his body. His arms started to shrink and feathers began to sprout. His nose transformed into a beak and his legs became thin and scaly. In no time, he was fully turned into a cock, pecking around the wizard's garden, living a completely different life from before.
One reason could be as a result of a magical spell gone wrong. Maybe a novice wizard was trying to turn a cock into a person but got the spell backwards. Another reason might be a curse from a nature spirit. If a person offended the spirit by harming the natural environment, the spirit could transform the person into a cock as a form of punishment.
Well, it could be due to some kind of time - related anomaly. In the world of Percy Jackson, there are all sorts of crazy time - based magic. Perhaps a time - traveling experiment by one of the gods or demigods went haywire and Percy got caught in it, reverting him to his childhood. It might also be part of a prophecy. There could be a prophecy that states Percy must relive his childhood for some greater purpose, like learning a lesson he missed the first time around.
In some turned into a girl stories, it could be due to a curse. For example, if someone offended an old witch or a powerful spirit, they might be cursed to change into a girl. Also, there could be a strange natural phenomenon. Like in a place full of strange energy, a person could be transformed into a girl just by being there for a while.
One reason could be a curse. Maybe she offended a powerful witch or magician, and as a punishment, she was turned into a mannequin. Another reason might be a deal with the devil - like figure. She made a Faustian bargain and the price was her transformation.
Betrayal could also be a cause. In some fictional tales, if a man betrayed his comrades or a powerful entity, that entity might use magic to turn him into a statue. It's a way of imprisoning him in a form that can't interact with the world anymore. For example, if a knight betrayed his king and made a pact with the enemy, the king's wizard could turn him into a statue.
It could be a scientific experiment. Scientists might be testing a new technology or drug that has unforeseen side effects, causing the transformation. This could then lead to a story about Otto Rocket trying to reverse the process while dealing with the new experiences of being a girl.
One reason could be punishment. If the girl has done something wrong like being cruel or disobedient in the story's world, a magical being might transform her into a cow as a form of justice.