The Slayer's Guide to Trolls (DnD Other)
From D&D Wiki
Trolls are a fundamental part of D&D games. Most adventures that move past the more basic goblins, run smack dab into the trolls. While technically giants, they fall on the smaller end of the spectrum. Fortunately, their regeneration more than makes up for their smaller size, making them a challenge for parties taking their first steps into the giant fighting fields.
Troll Physiology
Ferocious and bestial, most parties are taken aback the first time they come across a troll. Unlike the more 'civilized' goblin or other members of the giant species, a troll is unlikely to wear more than a bare minimum amount of armor, clothing, and it will likely be weaponless as well. Of course, this may not count for much, since the trolls natural claws, and teeth, serve the troll handily in battle.
Although a fully grown male weighs in at approximately five hundred pounds, a troll's lanky form can seem quite frail, which belies the surprising strength in their thin limbs. A troll's arms are long, and disproportionate to the rest of their body. The creature's posture is also stooped, causing it to drag its knuckles on the ground as it runs, which gives the troll a somewhat simian appearance. Its' skin coloration will fly in the face of this comparison, as troll flesh runs from a deep mossy green, to light and sickly grays, or even a mottled combination of the two. The skin is usually covered in warts or lumps, and from a distance can resemble scales. Thick, hairlike sprouts jut from the top of a troll's head, and are the sole source of hairlike substances on their bodies. These hairs writhe of their own accord, in response to their mood. While these movements may seem erratic to an outside observer, trolls are remarkably perceptive to their movements, and are able to discern the moods of other trolls by observing the motions of these hairs.