Nyx, Hecate and Nuit
In looking at the mythology of popular vampire fiction series, I find the emphasis on the goddess, Nyx, to be an odd choice.
Nyx is literally considered to be the originator power of the universe akin to the deified embodiment of the big bang theory. She is the creator of all things. However, there are no known temples in her honor and she is considered a secondary goddess that is typically depicted with at least one other god or goddess of a more primary focus.
When I stopped practicing Wicca, I began to study Thelema. It was at that time that I created the House of Nuit. As Nuit is a goddess specific to Thelema, her equivalent in the Egyptian pantheon would be Nut/Nuith. Both Nuit and Nut are sky goddesses, depicted as being covered with stars. Within Thelema, Nuit is said to be heaven itself.
Like Nyx, no specific ancient temples have been found but she is often seen in depictions. Although most vampire/vampyre are nocturnal, this does not necessarily equate to their goddess being one of the night.
Given this, I would argue that neither Nyx, nor Nuit, are specifically the goddesses of the vampire.
So who are the other candidates? Readily, we have Selene, Hecate, Artemis and Lilith. Others have even garnered that Lucifer was actually a female and, thus, the first of the vampire/vampyre as a fallen angel.
In the original myth, Selene is a moon and oracular goddess. She resides of the Temple at Delphi. So far as vampires/vampyres are psychic, I could see Selene being the goddess of the clairs or fortune tellers. Perhaps she could even be the goddess of there werewolf since she is of the moon but her abilities are of a narrower scope. Next is Hecate, goddess of witchcraft and the crossroads. She is the personification of female empowerment and the dark feminine. While Hecate seems a good candidate and is certainly a powerful goddess, I would contend she is not the goddess of the vampire/vampyre. What of Lilith? It is difficult to compare her to the pantheon of Nyx or the other Greek goddesses because she is of the Abrahamic lore. However, Lilith is depicted as a direct creation of the Abrahamic god and has wings. Of the candidates so far, she would be the most likely. Additionally, she is said to bear demonic offspring. This could widen her appeal and lineage to both female and male vampire/vampyre.
So the final candidate that is usually mentioned is Artemis. It is said that she cursed a man and created the first vampire/vampyre. This is a good origin story but I think there is a better candidate. And who do I think is the Greek goddess of the vampire/vampyre? Aphrodite. I know, a goddess known for love and sex may not immediately spring to mind when thinking of vampires/vampyres but there is reason. Aphrodite is also a dark goddess. There are legends linking her to being the eldest fate, thus possibly the daughter of Nyx. The son of Aphrodite, Eros, is also sometimes shown to originate from Nyx. She is also a sea goddess, which would link her to Echidna and Melusine and the dragon line. Many cultures have fused her with other goddesses including Inanna, Isis, Hathor, etc. Given the number of cults, temples, etc. dedicated to these goddesses, as well as the extent of their worship, Aphrodite seems the more obvious choice. https://www.thenotsoinnocentsabroad.com/blog/dendera-temple-of-hathor-one-of-the-best-temples-in-egypt
Additionally, she was known by the Romans as Venus-the light bringer. This terms ties her to both Samael/Lucifer, as well as Lilith in the Abrahamic faiths.
So what of the popular fiction series that featured Nyx as a Wiccan goddess, as well as the goddess of the vampire/vampyre? I will repeat the same thing I have said all along. Red Bird was Old Bird. The House of Night was the House of Nuit.
There is a main character in those books named Aphrodite, as well as Nicole and Zoey. The author later went on to write books about the goddess Venus. Only that author can detail where they obtained their inspiration and why they made certain choices.
For personal reasons, in relation to a House to which I once belonged, it is the statue of Aphrodite in the Egyptian vulture cap that is the most convincing for me.
Someone close to me once gave me this book, Triple Goddess by Adam McLean. It is heavy on the Greek pantheon of mythology but is a good introduction to the concept of the Triple Goddess. This book is interesting because it has references specifically to Nyx.