Nothing New Under the... Uh, Moon?

Having watched last night's episode of Buffy, I have only one thing to say: I am quite sure that the line "I'm what monsters have nightmares about" originally appeared in a Doctor Who novel.[*] Hmm. First we get some story elements and lines of dialog in Buffy and Firefly that are strangely remeniscent of Blake's 7, and now this... Coincidence? Well, probably, but it's kind of an interesting coincidence...

[*] In fact, a quick google tells me that it was on pg. 137 of Love and War. I love the internet.