Members of some species are generally considered among the "Verminous Races" - creatures which, while intelligent, are allegedly generally incapable of living in civilized society and are inherently savage or deceitful and dangerous. As a result, they are given Outsider status by default. This label only applies to living, natural creatures of the Material Plane - while creatures like demons, devils, or undead are also counted as "Outsiders", they belong into separate categories.
The following creatures are generally considered to be among the Verminous Races:
Adventure Ideas
Designer's Notes & Resources
Yes, this is very racist (or rather, speciesist). But the general attitude in Earth's 19th century was all too often similar to this.