N is for 'Nightmares'!
'Nightmares' is not a character, it is one of the most famous episodes of Buffy; the Vampire Slayer. It's one of the early ones, number 10 in Season One, I think, and it's considered one of the best episodes, depending on which list you read, lol! I won't give away too much of the plot, just that everyone is experiencing their nightmares and worst fears while they are awake, like Buffy's father telling her she's a terrible child and the reason her parents got divorced, Giles the Librarian/Watcher forgetting how to read, Xander's clothes disappearing in the middle of class.
Spike's not in this episode; he doesn't show up at all in the first season, He shows up in Season 2. Spike is my favorite - wonder what his nightmare would have been? ...Probably, now that I think of it, the events that happened to him for real were his worst nightmares. Poor baby :C