Legend of the White Snake
The Legend of the White Snake is a Chinese legend which existed orally before any written compilation. It has since become a major theme in several Chinese operas, films and TV series.
At its most basic, the story tells of a young scholar who falls in love with a beautiful woman, unaware that she is a white snake who has taken on a human form. A monk intervenes in order to save the scholar's soul and casts the white snake into a deep well at the Leifeng Pagoda.
Over the centuries the story has evolved from a horror story to a romance with the scholar and the white snake-woman genuinely in love with each other, but such a relationship is forbidden by the laws of Heaven. There have also been variations on technicalities of the story such as the scholar adopting the white snake as a pet while still a schoolboy; or himself being banished from Heaven and becoming a mere human on Earth.
An added character is a green snake who has also been turned into a woman and serves as the white snake-woman's companion and confidante.