Tellus: Fiends (Goblins, Ogres, Beastmen, whatever else)

The Lesser Fiends of Tellus are the weakest and, generally speaking, least threatening of their kind in so much as they are base and degraded creatures driven by desires. They very much overlap with the ideas presented in the Random World, namely that of the Goblins and Ogres. The key difference here is a (slightly) more lighthearted presentation in some cases and an overall more random/bizarre design.

Lesser Fiends

Final Fantasy II goblin.

As explained here, Fiends are born of the unbalance of mind/souls. It may take years, even centuries for such imbalance to manifest physically as a Fiend but in invariably will at some point. In time this taint could warp creatures or plants or, in most cases slowly create a corporeal body for a Fiend to manifest. Since it is much easier to become overwhelmed by raw emotions and obsessive desires, most Fiends are aligned toward Chaos/Black Magic: this has nothing to do with morality of this side of magic despite what Ulm culture says. Its simply the way people are. In any case, eventually the ambient spiritual and geomantic energies of the world are twisted into a knot and form a Fiend, most of which are lesser Fiend who are driven by extremely petty desires.

Fiends of such type are inherently wacky creatures: comically bizarre in their destructive urges at the best of times and unfortunately mad and dangerous at the worst of times. The weakest of barely more than animals, albeit inhabited by a wicked base intellect and an uncanny obsession. Usually this manifest in simple desires for simple things, namely gold, food or spreading violence. These creatures aren't a true-breeding race. They are not people. They are not something which can or should be played as a player character. 

While they fit in within the role of goblins, ogres and trolls this is not the only physical form they can have. This is where Tellus and the random world diverge more heavily despite drawing from the same ideas I tend to use. Fiends can be of any form, shape, size or even nature: some are more plant-like, some are more Elemental and others are even a form of Undead (which are normally rare in Tellus) even if their form is not the original's corpse. Indeed some have truly bizarre forms which mix and match organic and inorganic elements to a rather bizarre degree. Thus in this aspect the Fiends of Tellus draw heavily from the imagery of the more 'out there' monsters found in JRPG where there is seemingly no real limit to how weird the design can get. Ultros would be a good example of a Fiend.

Fiends as Non-Combat Encounters

Despite there seemingly 'evil' nature, not every Fiend needs to be killed, reduced to being nothing but a pile of HP and XP. Being extremely petty, yet also obsessive creatures driven by desire and needs they cannot control, Fiends can be easily bargained with or even tricked and manipulated during said bargains. After all, a creature driven by a lust for gold and ogling cute girls (or boys) can be rather easily manipulated to the party's end should they play their cards right.