Trolls are an evil race of Middle-earth, made in mockery of Ents. They were bred in the First Age by Melkor Morgoth in his dungeons. Trolls were not a major element in the Wars of Beleriand in the First Age, save that a Balrog chief had a bodyguard of trolls. In the Second and Third Ages, Sauron used trolls, but this was most likely frustrating, for trolls were severely limited by stupidity.

Trolls were very large creatures, roughly fourteen feet, the size of Ents, and had thick skin that varied in color by tribe or clan, and all had black, possibly acidic blood. Stone trolls, hill trolls, and cave trolls would turn to stone in sunlight. Only the Olog-hai trolls would not (Find out more about these clans, under the Groups and Clans heading, each with its own page). Trolls enjoyed killing Men, Elves, Dwarves, and anything else they could get their hands on. They would hoarde any treasure they would find, and after removing all valuables from their captives, they would eat them, usually raw, but sometimes cooked. By the end of the Third Age, trolls had become rather dangerous, for Sauron secretly increased their intelligence and their cruelty.