A troll is a class of being in Norse mythology and Scandinavian folklore. In Old Norse sources, beings described as trolls dwell in isolated rocks, mountains, or caves, live together in small family units, and are rarely helpful to human beings.Later, in Scandinavian folklore, trolls became beings in their own right, where they live far from human habitation, are not Christianized, and are considered dangerous to human beings. Depending on the source, their appearance varies greatly; trolls may be ugly and slow-witted, or look and behave exactly like human beings, with no particularly grotesque characteristic about them...
Terry Pratchett has developed an elaborate version of the world of trolls, including more than 40 named troll characters in the Discworld books, and providing them with an antipathy thread vis-a-vis the race of dwarves:
The traditional enmity between dwarfs and trolls has been explained away by one simple statement: one species is made of rock, the other is made of miners. But in truth the enmity is there because no one can remember when it wasn’t, and so it continues because everything is done in completely justifiable revenge for the revenge that was taken in response to the revenge for the vengeance that was taken earlier, and so on. Humans never do this sort of thing, much. (A Blink of the Screen)A summary, from The New Discwold Companion:
Trolls are a (usually) siliceous but humanoid life-form... a strong, hardy and incredibly long-lived race. And proverbially, and quite unfairly, considered to be as thick as two short, thick wooden things... the slowness of thought is induced by the effect of heat on the silicon troll brain. If sufficiently deep-frozen, a troll is astonishingly intelligent... trolls do not die except by accident or design. Left to themselves, trolls get bigger and slower and tend to settle in one place and think, very slowly and deliberately, about Things. They become more and more rock-like, a process that may take thousands of years. At some point they stop thinking, possibly because they have reached a kind of conclusion, but by then their thoughts are so slow that they are taking place against a geological timescale... (pg 229)
I've encountered a great many trolls in the rocks of Drift Inn: