Trolls bear no resemblance to the cute little dolls with big bug-eyes, dolphin grins, and bushy red hair. Rather, trolls are nasty monsters who can assume gigantic proportions and wreak havoc wherever they choose. They are fiendish giants, often associated with dark-side sorcerers.
To the old Norse, the term "troll" was applied only to hostile giants. By the time of the high Middle Ages, trolls had become a bit smaller and more fiendish, but they had also become capable of working black magic and sorcery. Regardless of their size, trolls are unrelenting enemies of humankind. Those occasional Scandinavian folk heroes who dared to engage them in mortal combat were able to defeat the trolls with their superior intelligence, rather than might of arm or sword. Trolls are most often quite slow-witted, and they become confused and weak if they can be somehow tricked into stepping out of their darkened caves into direct sunlight.
In more contemporary times, the troll is regarded as a denizen of mountain caves, larger than the average human, and exceedingly ugly, who often crouches under bridges waiting for unsuspecting victims.