A Troll.
A Troll is a type of monster found mainly in Norse mythology but has since spread into the realms of fairy tales and fantasy as a popular antagonist in countless tales - in the old tales trolls were seen as generally malignant and cruel humanoids of either gigantic size or small stature and were normally seen as hideously deformed, though they were often depicted with shape-shifting abilities and other magical powers.
Trolls lived in mountains, rocks and caves - normally solitary creatures they sometimes lived in small family groups consisting of either a mother and her son or a father and his daughter, they rarely helped others and were often depicted as man-eaters, tricksters and violent: later tales told of how Trolls would turn to stone or explode if exposed to direct sunlight and for this reason many landmarks in Scandivia are attributed to Trolls.
Trolls are also said to be able to smell the blood of Christians and like many pagan-spirits go into a rage upon finding Christians near their territories, the reasoning behid this is that Trolls once ruled Norway and the surrounding lands but the arrival of Christianity robbed them of their previous power, forcing them to flee into the wilderness and the bells of traditional churches hurt the Trolls ears (being sensitive to the sound of bells).
Legends persist of trolls who would throw large boulders at churches in anger and perhaps vengeance for these percieved wrongs but it is generally believed that the Trolls (much like other fairy folk) ultimately disappeared from Norway sometime in the past, though some people still like to envision them as being real beings (usually this is more for tourism or entertainment, very few believe in them as active supernatural forces in today's world).