xhonzi said:

How critical are "monsters" to the Star Wars fiction?

ANH
Krayt Dragon (call and skeleton)
Dewbacks
Banthas
Dianoga

ESB
Wampa
Tauntaun
Space slug
Whatever eats R2

RotJ
Rancor
Sarlaac

It seems like something I don't strictly care about, but has always been a focus of the OT. I don't think a lot of the EU concerns itself with monster scenes. Unless it's reusing stuff from the OT.

I think the monsters in the OT were all a lot of fun, adding to the whole galactic fantasy feel.

The EU is too busy writing treatises on the nature of good and evil to worry about fighting monsters. Except that rancors exist on every planet in the galaxy.