The China Doll is the titular antagonist of a popular ghost story, though variants of the story exist in many different forms - it takes the horror icon of a possessed doll and plays on many people's fears of such items, while it is still told as a ghost story in many areas the nature of the story plays into the nature of creepypastas and urban legends, which has made some believe that parts of the story are either fictionalized portrayals of true events or based on actual supernatural legends, neither of which have much evidence behind them.
China Doll Story (First Incarnation)
The ghost story begins with a child (usually named Emily) who convinces her parents to buy her a China Doll and is soon haunted at night by a voice that states:
"Emily I'm at the stairs"
"Emily I'm on the top step"
"Emily I'm at your door"
"Emily I'm in your room"
"Emily I'm at your bed"
after this occurs the fate of Emily is usually pretty graphic, with her family finding her dead in a closet with her eyes removed and replaced with china eyes - alternate versions have Emily and her entire family murdered by the doll and when police arrive the doll ends with a chilling message:
"police, I'm behind you".
these variants of the story share a lot in common with the Man Upstairs, who taunted his victim in a similar manner - there is also a popular urban legend concerning a similar phone-based killer complete with lines such as "I'm coming up the stairs".
China Doll Story (Variant)
Such variant of the China Doll story involves a child who obtains a China Doll but is terrified of the thing, becoming convinced it is watching them - the child continually goes to their parents to complain about the doll but are dismissed each time.
Then in the morning the parents enter their child's room and finds the child dead in the closet with their eyes removed and replaced with those of the china doll's.
This variant of the story is very similar to the methods of the Mystery Killer in "There's A Man At My Window" - another popular ghost story / urban legend involving a child and disbelieving parents.