Sadako Yamamura is probably the most iconic onryō (vengeful ghost) character in Japan. She is the main antagonist in the Ring franchise. With long, black hair covering the face, and a white dress, Sadako has inspired the looks of other horror icons as well. (ノдヽ)

Trivia~
- In the novel version of the story, Sadako has a Testicular Feminization Syndrome, which means she has a female appearance but also has a pair of testes. She can also manipulate her powers to manifest some sort of virus, which kills her victims in a span of 7 days.

- Sadako was split into two forms when she was younger. One was good and the other was evil. The evil half was hidden away by Sadako’s father, while the good half continued on with her life (she even joined an acting troupe) until she was murdered, which was also the time the good and the evil Sadako became one again.

- Sadako’s most notable power is Nensha, which allowed her to etch her negative energy and hatred into a videotape while trapped inside a well.

~

Reference: http://ring.wikia.com/wiki/Sadako_Yamamura