I'm writing an essay on RISE OF THE GUARDIANS, which involves conceptual entities that need belief to function.
Aside from religious fiction, what fictional precursors exist for this sort of thing?
Tinkerbelle in PETER PAN is probably the best known character who comes alive thanks to belief, though in general the fairies of Barrie's world don't need human belief.
In MIRACLE ON 34TH STREET Santa Claus isn't actually affected by human disbelief, but he goes out of his way to encourage belief in his existence.
Most will remember the STAR TREK episode "Who Mourns for Adonais," in which aliens who pretended to be gods to ancient humans seemed to need human belief, and retired to some netherworld when they didn't get it.
I know there's got to be tons of fantasy-novels in which magical gods diminish for lack of belief, but the only one I can think of right now is Charles deLint's JACK THE GIANT KILLER and its one sequel.