I've heard that Ghostbusters was influenced by H.P. Lovecraft's writing. I was wondering if there was a particular piece that Ghostbusters was drawn from or was it a more general influence?

More of a general influence.

The idea of a mad architect leading a cult in the worship and service of an ancient god is very much in the Lovecraft tone.

There is another Lovecraftian entity called Shub-Niggurath (“many Shubs and Zuuls…”) which suggests that Aykroyd probably had HPL on his mind when he cooked up the first movie.

There was the direct reference to Lovecraft in the RGB episode when they fight Chthulu (a Lovecraft elder god), but of course this was by another author. It does however, again show that a lot of people saw the HPL-esque nature to parts of the movie.

There's probably more…
Anybody else have any thoughts?