Sadako Yamamura (山村 貞子 Yamamura Sadako ) is the antagonist in Koji Suzuki's novel Ring and the 1998 film adaptation. She returns as the antagonist in Rasen and the protagonist in Ring 0: Birthday, and appears in the Korean and American remakes of the Ring Trilogy, although as different characters.
Her name combines the Japanese words for "chaste" (sada) and "child" (ko).
Sadako's character is not directly portrayed in Ring until the final scenes of the film, but is expanded briefly in Rasen and to a much greater extent in Ring 0: Birthday, although there are differences in these various portrayals.
In all versions of the Ring cycle, she appears as a shadowy young woman dressed in white, whose face is concealed behind her long black hair. The first film explains that, as a young girl, she was thrown into a deep well and left to die. Her spirit survived, however, and put itself into a videotape that kills anyone who views it unless someone else watches it within seven days. If not, Sadako herself emerges from the television screen, and the viewer dies of fright.
Most other incarnations share one thing in common: Sadako's need to reproduce, something she can not do herself, as she is portrayed as an intersexual. This is generally the reason why she creates the "Ring Virus", since she will "live on" in it, as long as her DNA (merged with that of the smallpox virus) still exists. In some incarnations, the "Ring Virus" is simply treated as a mysterious phenomenon rather than a biological virus; in these versions, she is portrayed as having created it to wreak vengeance on humanity.
The filmed version of Ring 0: Birthday introduced the concept of two Sadakos—an idea not present in the earlier Ring books or films. The movie implies that after her mother is mocked and insulted by reporters at her demonstration, Sadako killed the reporter who started the chaos with her powers, and split into two identical girls—one relatively normal, the other evil and insane. This second Sadako is imprisoned by her father and drugged so that she would not physically mature. The second Sadako is never seen clearly, so it is not made clear just what her physical state is, only that she has the size and proportions of a child.
Both Sadakos possess psychic powers, although it is never clear whether they are the same. The "normal" Sadako exhibits, at one point, healing powers and the ability to see ghosts. She is also linked to the other Sadako, who wields more destructive powers (such as psychokinesis) and uses them to defend the "normal" Sadako when she is under distress—even if it is her own powers causing said distress.
After "normal" Sadako is murdered, the evil Sadako merges with her. This merger involves no physical contact, as the child Sadako is locked in a room when it occurs (and vanishes afterwards), and two characters watching over the nearby corpse of older Sadako witnesses only the reanimation of her corpse.
The "restored" Sadako acts like her younger, evil self, but her appearance is based on her older self, although her face is obscured by her hair and she moves mostly in shadow.
Sadako's initial origin story differs between the novels and films. In the novels, she is born to Shizuko Yamamura and Dr. Heihachiro Ikuma. Ikuma convinces Shizuko to give a public demonstration of her psychic powers. However, Shizuko bows out of the demonstration due to migraines brought on by her powers and is labelled a fraud by the press. Shizuko eventually goes into a deep depression and commits suicide by jumping into Oshima Island's volcano, which Shizuko had correctly predicted would erupt at a specific date and time. Sadako remains living with her family on the island, while Ikuma attempts to awaken potential psychic powers within himself by standing under waterfalls. This experiment succeeds only in making him sick, and he is hospitalized for many years.
At the age of nineteen, Sadako joins a Tokyo-based acting troupe and falls in love with the sound operator, Hiroshi Toyama. He learns of her powers but accepts them. Unfortunately, an early form of the curse is created in the form of a sound recording which kills four people including the troupe's director, resulting in a heartbroken Sadako leaving Toyama. Sadako visits Ikuma in hospital, only to be raped by a doctor named Nagao Jotaro. However, he discovers that she is a hermaphrodite, and possesses testicles in addition to a vagina. When Sadako attacks him with her powers, Nagao throws her down a nearby well and seals her within. Foreseeing herself being reborn years later, Sadako vows revenge on the world before she dies.
Her past alters in the films after the demonstration. During which, a journalist named Miyaji accuses Shizuko of being a fraud. Enraged, Sadako kills him using her powers, giving him a heart attack, which would later become Sadako's preferred method of killing. At this point, Sadako splits apart into two identical girls. One is kind and gentle, the other wrathful and destructive. After Shizuko's suicide, Ikuma moves to Izu County where he locks up the evil twin and drugs her to prevent her from aging, but allows the good twin to live a normal life. As in the novels, the good Sadako joins the acting troupe and falls in love with Toyama. However, Miyaji's wife Akiko arrives to avenge her husband. Sadako's evil twin calls out her other self, causing her to lose control of her powers and murder a doctor that came on stage to help her. The troupe members, except for Toyama, kill the good twin, and drive to Ikuma's house to kill the evil one, only for her to escape and bond with her revived good self. Unable to recognise friend from foe, Sadako goes on a murderous rampage and kills the entire troupe, including Toyama. The good Sadako re-emerges only to be attacked by a distraught Ikuma and pushed down the well.
During her entrapment, a summer resort is built over the well. Using her powers, Sadako projects a series of images from her past into a cursed videotape which, when watched, kills the viewer after seven days. In the films, it is revealed Sadako survived down the well for over 30 years by sheer will, but died after creating the videotape. In the second novel, Spiral, Sadako is able to resurrect herself using Ando Mitsuo, Mai Takano, and the effects of the Ring Virus as catalysts. Sadako also resurrects Ryuji Takayama and later Ando's dead son, in exchange for selling the journal of Kazuyuki Asakawa to spread her virus. In Ring 2, Sadako remains a ghost and seemingly remains trapped, asking Mai and Yoichi Asakawa why they can escape from the well while she cannot.
The most recognizable image of Sadako is a shadowy young woman whose face is hidden behind long black hair. She is often seen crawling out of a television screen, usually just after a depiction of her crawling out of a well. This appearance is typical of yūrei, a kind of Japanese ghost bound to the physical world through strong emotions which do not allow them to pass on. Specifically, Sadako is a type of yūrei known as an onryō, bound by a desire for vengeance.
Like many creatures of folklore, yūrei have a traditional appearance and follow a certain set of rules. They are generally depicted as female, although the legends also include male yūrei. They wear white clothing, which is the color of clothing that corpses are traditionally dressed with in Japan. They have long, often unkempt black hair and white faces, which comes from Kabuki theater where each character has a particular type of wig and make-up that identifies them to the audience. (Although it may also come from the fact that while Japanese women usually wore their hair in a bun, for funeral and burial, their long hair is let loose)
In addition to the standard yūrei appearance, Sadako is also an amalgamation of two famous Japanese ghosts, Oiwa and Okiku. From Oiwa, Sadako takes the single, misshapen eye. From Okiku, the style of murder, of being thrown down a well and then having the ghost rise from the well to seek vengeance.
The success of the 1998 film Ring brought the image of the yūrei to Western popular culture for the first time, although the image has existed in Japan for centuries. This image is often used in J-Horror films, such as Ju-on (and its remake The Grudge), One Missed Call and Dark Water.
Sadako is also based on the life of early-20th century psychic Sadako Takahashi, an apparent practitioner of nensha, the art of projecting images onto film by thought alone. In 1931 Takahashi was studied by psychologist Tomokichi Fukurai for his book, Clairvoyance and Thoughtography". 
Sadako has a variety of psychic powers throughout all the Ring cycle books and films. The most famous is her ability to create the "cursed" video tape.
In the films her method of killing with the video curse is not explained, but when someone is killed by it she is seen climbing out of the nearest reflective surface (the most famous portrayal of this being her crawl from a television screen) and approaching them. The corpses are discovered with looks of unearthly anguish on their faces, so it could be presumed that they "die of fright", i.e. a heart attack. In Spiral, the curse is explained in detail, and is discovered to in fact be a virus. When someone watches the cursed tape (or something else carrying the curse) some of their DNA is changed to become that of the Ring Virus (i.e. a hybrid of Sadako's DNA and that of the smallpox virus). This travels through their body and in most cases causes a sarcoma to form on one of the arteries of their heart. If the curse has not been appeased within seven days, the sarcoma detaches from the artery and clogs it, causing heart failure. Eventually, however, the Ring virus is able to infect people through means other than videotapes, such as a report detailing the events of Ring written by Asakawa which the virus had entered from Asakawa's body, a novel version of the report published by Asakawa's brother, a movie based on the novel (which Sadako was cast as herself in), and finally the Metastatic Human Cancer virus, a mutated form of the virus which escaped the Loop and plagued the real world.
In Ring 0 Sadako exhibits a variety of abilities (mentioned above), including telekinesis, the ability to kill people instantly with psychic powers, healing abilities, ESP, and possibly the ability to split herself into two beings and merge them again.
In Ring 2 the protagonists discover that Sadako was alive in the well for 30 years, dying shortly before she was uncovered in the previous film by Reiko Asakawa. This implies that she had remained alive until she imparted her curse onto the tape, meaning that she also had superhuman endurance and longevity, as well as inedia (the ability to live for extended periods without nourishment).
In the original Japanese films, Sadako's tapes cause their victims to have odd and malformed images when photographed. These images remain until Sadako kills the victim.
Lastly, she imparts her curse onto the video tapes, implying the ability of projected thermography.
Park Eun-Suh more closely resembles the Sadako from the novels. She appears to be about the same age as Sadako, though her age is never confirmed. She and her mother both had supernatural powers (similar to Sadako and Shizuko) and were rumored to be witches. After Eun-Suh's mother throws herself off a cliff into the sea, Eun-Suh's powers mysteriously disappear. As she grows older, she works at a nightclub under the name "Sunny Park". Due to her powers, she is a suspect in the death of one of her co-workers.
Eun-Suh is raped by her half brother shortly before her death, during which he discovers that she is a hermaphrodite. She telepathically threatens to kill him if he told anyone. Horrified, he chokes her unconscious and drops her in a nearby well.
Sadako was the main influence on Samara Morgan from the 2002 American remake, The Ring, and its sequel, The Ring Two. She was played by Daveigh Chase and Kelly Stables. Samara Morgan is depicted as an otherworldly little girl (Born 1970, died 1978) responsible for the creation of the cursed videotape from the American version of the Ringu story. Her usual appearance is of a girl with long, dark hair covering her face and wearing a white dress. Samara possesses the power of nensha (thoughtography), capable of burning images onto surfaces and into the minds of others. Using these powers, Samara makes the cursed videotape with her own thoughts, and imbues it with the power to kill the viewer within seven days. She also has other abilities such as possession, water manipulation, and the power to climb out of electrical screens like television sets. In the short film Rings, a character tries to prevent Samara's escape from a television set by breaking the screen, but she then tries to emerge through the screen of a video camera as the character records her appearance.
Samara's history is covered through the American films. The Ring explains that Samara is adopted by Anna and Richard Morgan (Shannon Cochran and Brian Cox), who own a horse ranch on Moesko Island, Washington. As Samara grows older, her powers burn horrible images into her adoptive mother's mind, nearly driving her insane. Richard banishes Samara to live in the ranch's barn, but she uses her powers to drive Anna's beloved horses to suicide. At some point, Samara is taken to a psychiatric hospital but the doctors are unable to explain how she created the images. During a family vacation on Shelter Mountain, Anna attacks Samara as she stands before an old well, suffocating her with a garbage bag and then dropping her down the well. Anna then commits suicide by jumping off a cliff. However, Samara clings to life for seven days alone in the well before dying of hypothermia.
Eventually, a set of rental cabins are built near the well, one on top of it. This allows Samara to project her visions into a VCR tape, creating the seven-day curse. In The Ring, Samara's curse kills Katie, the niece of journalist Rachel Keller (Naomi Watts), who investigates the tape's origins. Rachel, her ex-boyfriend Noah Clay (Martin Henderson) and their son Aidan (David Dorfman) all watch the video. Rachel meets Richard, who warns her to stay away and then kills himself. Rachel and Noah eventually find Samara's corpse in the well and bury it, but this releases a corporeal form of Samara's spirit and she later kills Noah. Rachel destroys the original video cassette in a fit of rage, but uses a copied version of the video to continue the curse in order to save Aidan.
The Ring Two expands upon Samara's backstory: Her mother, a woman named Evelyn, believed that her daughter had a demon inside her and tried to drown the girl, but she was prevented by nuns. Evelyn is sent to an insane asylum, while Samara was put up for adoption. In the film's present timeline, Samara deliberately manipulates the tape to get back to Rachel, having decided to make Rachel her new mother. After Rachel burns the tape, Samara possesses Aidan. Rachel drugs Samara and then nearly drowns Aidan to pull Samara out of his body. Samara retreats to a television set, Rachel being willingly pulled into Samara's visionary world and down the well. Rachel climbs out of the well with Samara pursuing her, but Rachel covers the seal on the well just in time.
Tabitha is the parody of Sadako and Samara's character in Scary Movie 3. She is first introduced at the beginning of the movie when she kills two women named Becka (Jenny McCarthy) and Katy (Pamela Anderson). Later she gets into a fist fight with Brenda Meeks (Regina King), resulting in Brenda's death. At the end of the movie she is confronted by protagonists Cindy (Anna Faris), George (Simon Rex) and Cody (Drew Mikuska), who offer her a place in their family. She appears to accept, but then reveals she is faking and tries to kill them all with a chainsaw. President Harris (Leslie Nielsen) knocks her down the well, and Cindy and George seal it with the cover.
The Dutch metal band Thanatos released a song titled "The Sign of Sadako" on their album, Undead, Unholy, Divine. The lyrics directly relate to the character, with lines such as "One became two, then two became one" (referring to the splitting into good/evil Sadako, and subsequent remerging) and "The curse was spread and visualized/Watch the images within seven days you'll die".
Like many aspects and symbols of Japanese pop culture, she has also been referred to by 2ch and 4chan in memetic fanart depicting her in a more positive way. She has been called "Japan's most popular psychic ghost."
The Sadako, Eun-Suh, Samara, and Tabitha characters are played by a number of different actresses:
- Rie Inō - Ring, Ring 2
- Hinako Saeki - Rasen
- Ayane Miura - Ring: Kanzenban
- Tae Kimura - Ring: The Final Chapter, Rasen
- Yukie Nakama - Ring 0: Birthday
- Ai Hashimoto - Sadako 3D
- "Not only was Koji Suzuki -- the author of the Ring novels -- familiar with the history of Japanese parapsychology, but the story of Tomokichi Fukurai significantly influenced him as he wrote the first novel in the Ring trilogy." Kristen Lacefield, ed., The Scary Screen: Media Anxiety in 'The Ring'. Surrey, England and Burlington, VT, USA: Ashgate, 2010.