Troll
(from encarta)
Troll, in Scandinavian mythology, a powerful giant that was an enemy of humans. Trolls lived in caves or in castles on hilltops, robbing and eating any travelers foolish enough to stray into their domain after dark. Huge, hard-skinned, and virtually indestructible, they could only be vanquished by sunlight, which would either turn them to stone or make them explode.

In later folklore, trolls were less awesome and malevolent. They committed specific acts of malice, such as stealing maidens, and also began to develop semimagical powers such as prophecy and shape-shifting. Outside Scandinavia trolls began to be associated with stories of the so-called little people who lived in mounds on the outer limits of cultivated land and performed acts of mischief.