In the story "Coraline", who is the "other mother"?

Coraline’s other mother is described to look like an alien might look. She’s tall and slender with long fingers and hair that floats in the air like seaweed in water or wriggling snakes. She has eyes that look like huge black buttons. When Coraline first sees her other mother she believes she has some similarities to her real mother. Just before she takes the children’s souls, her parents and the cat back to the real world, Coraline realizes that she can’t believe she ever thought this creature looked anything like her real mother.

The other mother is an evil creature. She intentionally lures children into her world where she steals their hearts, souls and memories from them. As the children tell Coraline, she leaves them as empty shells. She has created a house and grounds similar to the one in which Corline lives with the exception that Coraline’s room is filled with things she finds interesting. The other mother also tries to entice Coraline by cooking her the foods that she likes and offering her treats and extra attention. When the other mother is angry, she takes out her anger on the things that she has created. For instance, she locks Coraline’s bloated, deformed other father in the cellar when he tells Coraline too much about the other mother’s creations.

The other mother agrees to release the children’s souls, Coraline and Coraline’s parents if Coraline can locate the three souls and her parents. When Coraline asks for proof that the other mother will let her and the others go free, the other mother first promises on her mother’s grave. She proves how cruel a person she is when she tells Coraline that she put her mother in the grave when she was still alive, then put her back when she tried to crawl back out. Coraline is more satisfied when the other mother agrees to promise on her right hand, as it seems this promise might be more likely to stand since the other mother will actually have flesh in the deal.