Hill-Troll in the New Line film
Trolls of the hills of Middle-Earth. It is not clear which hills they were from. They could have been from Dunland, a hilly part of the Misty Mountains, or the Trollshaws in Eriador. It is known that hill-trolls were not simply lumbery beasts that could not think. They were, in fact, servants of Sauron. Though other Trolls were evil, most were unaware of Sauron's existence. Now the Hill-Trolls may have marched to war for Sauron, but since trolls were so stupid, this is unlikely. They were probably captured by Mountain Orcs and brought to Mordor, where Sauron made them march to war. Hill-Trolls did fight in the War of the Ring. They made an appearance at the Battle of Pelennor Fields, where they knocked down gates in Minas Tirith in order to kill people. They may have even helped the Great Beasts pull Grond. They were all killed, and made no other known appearance.