My Baby Doll

This trope is when a mother, in a delusion, thinks that a doll is her child. It can be caused by guilt due to Parental Abandonment, trauma or artificial means. But no matter the means, the result is that the mother treats a doll as her child. Whenever the real child interacts with his mother, she treats him as an impostor to take the place of her child, for added irony and sadness. The best case scenario is that the mother is so wrapped up that she doesn't even realize that her real child is standing in front of her and the mother thinks that the child is a stranger. It can involve The Doll Episode.

Artificial Humans and Replacement Goldfish are different, as the original child is still alive. Also, being a Living Doll Collector is not this.

Examples of My Baby Doll include:

Anime and Manga

The Ur Example is Kyoko Zeppelin Soryu from Neon Genesis Evangelion. After the contact experiment with Unit 02, this fractured her psyche and led to her belief that the doll was Asuka. However, due to her psychotic nature, she decapitated at least one of the dolls and then committed a 'murder-suicide' with another. A young Asuka was the first to discover such a scene.
In The Familiar of Zero, Tabitha's mother drank a spiked drink meant for Tabitha, who is actually the next in line for the Galian throne. This resulted in her losing her mind and thinking that Tabitha's childhood doll was Tabitha herself, and that her daughter was an impostor sent to replace the doll. This leads to Tabitha leaving and adopting the name of her doll, Tabitha.
In Tales of Symphonia, Raine's mother has Soryu Syndrome due to the guilt of sending her and her brother Genius through the Otherwordly Gate and not being able to go through, too. Also, the loss of her husband (a human) didn't help. This results in her living in a house on Exile talking to a doll as if it were a 5-year-old Raine. The problem is that a now fully grown Raine is trying to get her to realize she [Raine] is her daughter. Unlike the other examples, the mother isn't hostile to real Raine and is friendly but still doesn't recognize Raine as her daughter.
Joy from Psychoville has a doll called "Freddie" that she is convinced is her real child. She even steals blood from the hospital where she works to give Freddie transfusions.