Doc Fritz;164904
And nobody mentioned the interesting fact that “Zuul” is also the (apparent) individual name of the Gate Keeper. Which could mean any of number of things, such as “Zuul” was a name for the terror dog “race”, or the Gate Keeper used to be a member of the Zuul species.

It's all left intentionally vague, of course.

Doc Fritz;164904
And nobody mentioned the interesting fact that “Zuul” is also the (apparent) individual name of the Gate Keeper. Which could mean any of number of things, such as “Zuul” was a name for the terror dog “race”, or the Gate Keeper used to be a member of the Zuul species.

It's all left intentionally vague, of course.

StaypuftX;165450
I think it was meant to inform us what Gozer does, as it's obviously travelled to various other inhabited worlds/dimensions and destroyed/conquered them. Vinz seemed to assume Egon knew what he was talking about.

I dunno… Vinz seemed to be… like a young child explaining their favorite TV show/story to someone, assuming they know what they're talking about.

Many shubs and zuuls

the sight of the Ancient Ones is a blasphemy to the ordinary senses of a man, for they come from a world that is not straight, but crooked, and their existance is of forms unnatural and painful to the eye and to the mind, whereby the spirit is threatened and wrenches loose from the body in flight, and for that reason the fearful utukku xul take possesion of the body and dwell therein untill the Priest banish them back to whence they came and the normal spirit may return to its erstwhile neighborhood. And there are ALLU, frightening dog-faced demons that are the Messengers of the Gods of Prey, and that chew on the very bones of a man.

Devil Master;167313
I think that, realistically speaking, at least part of this comes from Lovecraft. “Shubs” reminds me of SHUB-Niggurath. And the so-called Simon Necronomicon has this interesting quote:

Demons called XUL who possess people? And dog-faced demons? Something's very familiar…