Land spirits (Old Norse landvættir) are, as the name implies, the spirits who dwell within particular places or features of the land. They wield considerable influence over the well-being of the land and all who depend on it.
They can bless or curse those who live or travel within their land, and be blessed or cursed by them in turn. They’re fierce protectors of their native lands, seldom tolerant of mistreatment and dishonor, and seem to have a very passionate disposition in general.
The pre-Christian Germanic peoples seem to have taken great care to maintain the land spirits’ favor. For example, the first law code of Iceland (930 CE) instructed those entering the country by ship to remove the dragon-heads from their boats when they sighted land, lest they frighten the land spirits.
Just as there’s no absolutely distinct line between the land spirits and the gods, the lines that separate the land spirits from the elves, dwarves, and giants are blurry as well.
As with the elves, the worship of the land spirits continued long after the Germanic peoples were officially converted to Christianity and the veneration of the gods had ceased.