Trolls are large, stupid monsters that live underground, in caves, or under bridges.
One of the few specimens of a troll found in the wild was one that had taken residence in the Eastlands after the fall of the Empire. The Evil One also used a troll to guard the entrance to Witchville.
Leonardo Flathead made a major treatise proved that the world actually rests on the head of an enormous troll, rather than the back of a giant turtle.
A huge hairy Troll is found in one of the rooms under the White house. As Bivotar and Juranda are exploring, he leaps out of the shadows, blocking one of the exits. He brandishes a bloody axe, and spits angry snarls at Bivotar. The presence of the Troll activates a bluish glow on the Sword of Zork; guided by its energy, Bivotar defeats the Troll, who vanishes.
A few trolls were guards in the Castle of Zork and were loyal enough to stay even when the castle was deserted. One of them was smarte enough that he could speak (though slowly and quite poorly); he is very strong and can't control his movements; even a friendly patting can cause injury.