I haven't been getting much sleep lately because a few local trolls keep getting into my garbage at night.
I think that they must be forest trolls because they seem to travel in packs and the larger mountain trolls are usually seen alone.
Forest trolls are said to live in underground complexes, accessible from underneath large boulders in the forests or in the mountains. In their living quarters, they hoard gold and treasures.
Opinion varies as to whether or not the trolls are thoroughly bad or not, but often they treat people as they are treated. Trolls can cause great harm when feeling vindictive or playful, and regardless of other things they have always been feared.
Trolls are also great thieves, and like to steal from the food that the farmers have stored (or broken magical items from my garbage cans). Trolls can enter the homes invisibly during feasts and eat all the food, or spoil the making of beer and bread so that they failed or did not end up plentiful enough.
The trolls sometimes abduct people to live as slaves or at least prisoners among them. These poor souls are known as bergtagna ("those taken to/by the mountain"), which also is the Scandinavian word for having been spirited away. To be bergtagen does not only refer to the disappearance of the person, but also that upon returning, he or she has been struck with insanity or apathy caused by the trolls.
Anyone can be taken by the trolls, even cattle, but at the greatest risk were women who had just given birth and babies. Occasionally, the trolls steal a new-born baby, leaving their own offspring – a bortbyting ("changeling") – in return.
To ward off the trolls you can always trust in Christianity: Church bells, a cross or even words like "Jesus" or "Christ" are supposed to work against them. Like other Scandinavian folklore creatures they also fear steel.