Zoey Redbird is the central protagonist throughout most of the books. She's the fledgling with the unique crescent moon mark and an affinity for all five elements, which is super rare. The story follows her from being Marked and entering the Tulsa House of Night school, dealing with the whole Neferet situation, and navigating her complicated relationships. I mean, her circle includes a lot of the other main characters too—like her best friend Stevie Rae, the red fledgling who becomes the first undead High Priestess, and Aphrodite, who starts off as the mean girl but ends up being a crucial prophetess. Then there's the whole love triangle, or more like a polygon, with Heath, her human ex-boyfriend she's still connected to, Erik Night the hot actor fledgling, and Stark, the red fledgling archer who becomes her Guardian. Honestly, the cast around her is huge and sometimes hard to keep track of.
Neferet is arguably just as central as an antagonist. She's the High Priestess of Tulsa's House of Night who turns out to be consorting with Darkness and manipulating everyone. Her descent into outright villainy drives so much of the series' conflict. Kalona also becomes a major figure after he's freed—the immortal, fallen Warrior who battles Zoey and her group. The list feels endless when you consider all the important vampyres and humans that cycle through Zoey's life.