In Daphne Du Maurier's Rebecca, the narrator remains nameless in order to convey the overpowering essence of Rebecca, Maxim's dead wife and former mistress of Manderley; and to display without question the narrator's complete lack of power in her new home.
When she becomes Maxim de Winter's second wife, she believes that she will become the mistress of his home: not in a way that she will command others, but that she will bring their home to life, resurrecting joy and pleasure to her new husband's life. (She has no way of knowing that these things were not present when Rebecca was alive: his life was a living hell.) However, even the house seems to conspire against her fondest desire—it is as unwelcoming as a jealous woman:
There was Manderley, our Manderley, secretive and silent as it had always been...As I stood there, hushed and still, I could swear that the house was not an empty shell but lived and breathed as it had lived before...
While Maxim seems to love his new wife, he is somewhat distracted and never seems to notice when Mrs. Danvers (the housekeeper who was dedicated to—obsessed with—Rebecca) treats her as a non-person, which promotes the sense that the narrator is an outsider:
"I shan't want to make any changes." I stopped, a little breathless, still uncertain of myself and whether I was saying the right thing.
Mrs. Danvers does nothing to alleviate the narrator's nervousness or desire to avoid disrupting the household.
"Very good," she said; "I hope I shall do everything to your satisfaction. The house has been in my charge now for more than a year, and Mr. De Winter has never complained."
Mrs. Danvers rubs the narrator's face in her "alien status:"
"It was very different when the late Mrs. de Winter was alive...and though I managed for her, she liked to supervise things herself."
This is the housekeeper's way of demonstrating the power Rebecca had and the power Mrs. Danvers has, inferring that the narrator has no power, even though Rebecca is dead.
Once again I had the impression that she chose her words with care, that she was feeling her way, as it were, into my mind, and watching for the effect upon my face...into her face came the same expression I had noticed before, when I first had shaken hands with her in the hall, a look surely of derision, of definite contempt.
The narrator does not give her own name, and Maxim refers to her with endearments. Mrs. Danvers does nothing to recognize the narrator as a person of worth. In this way, Danvers makes the narrator feel weak, small and invisible. Danvers easily manipulates the new wife. In this way, Danvers keeps the poisonous atmosphere that Rebecca created in their home thriving, like a living thing. It drives a wedge between the newlyweds, and feeds Danvers desire to see the new Mrs. de Winter thrive.
The narrator is unnamed as if she were unimportant and not worthy of Danver's notice—as she keeps the memory of the dead Rebecca alive, still wreaking havoc in her wake as if she had never passed away.