Much of what we know about Scandinavian mythology during the time of the Vikings is found in myths and legends written down in Iceland after the Norwegian descendants on this island, as well as most of Scandinavia, had been converted to Christianity. Among this literature we find tales concerning the corporeal undead who dwelled in their burial mounds.
In the sagas written in Iceland, the name most common for such a revenant is draugr. In most of the sagas, such a revenant is not hostile unless its dwelling place is invaded by mortal seeking treasures buried in the mound. But, in some of the sagas, the dead person leaves his mound to inflict revenge upon the living who had brought about his death.
In the folklore of Norway recorded during the past two centuries, the draug (note difference in spelling) is most often a person who drowned in the sea but remains as a living corpse. In most of these tales, the draug climbs aboard ships or onto the shore to attack the living unless he is repelled. In this later Christian lore, a recurring theme is that the drowned person became a revenant as the result of not being buried in the consecrated ground of a church yard cemetery.