Half-Trolls

Half trolls were a name coined for men who belonged to the southern part of Harad. They came to fight the Battle of the Pelennor Fields and were loyal to Sauron. In appearance, they were black-skinned, having white eyes and a red tongue.

An uncertain term, half trolls may be referred to as creatures who were half-troll and half men or it may also be used as a simile to address a group of men from Harad who were giant in size and terrifying in nature. mThe term is still uncertain because they are only mentioned once during the Battle of the Pelennor Fields along with other members of Sauron’s army. "...out of Far Harad black men like half-trolls with white eyes and red tongues."

Purely based on the above citation, it seems as if Tolkein used the term half-trolls more as a literary effect and less to imply some kind of cross-breeding. However, the same chapter reveals a direct reference to “troll men” who were clearly shown as an equivalent to “half trolls” which adds to the possibility that these half-trolls did carry troll blood within them. Outside of these two citations, half-trolls or troll-men are not referenced anywhere else. So it is inconclusive to determine whether half-trolls were there in Middle Earth. A more likely possibility is that these men from south of Harad were so huge and fierce that they could be meaningly compared to the trolls.

According to Christopher Tolkein, the youngest son of J.R.R Tolkein, half-trolls were inspired by a character in Thiðrekssaga, who was an offspring of a woman and an incubus.
He appeared “troll-like” with his black hair and a black beard.

Sauran bred half-trolls through cross-breeding between a union of Olog-Hai and the Variags (Men from Khand). These beings were seven feet in height and had dark skin.

The creature "Half-trolls of Far Harad" is able to strike twice on a player.

In this game, the half-trolls are known as the “Mahud Men” from Far Harad. They were heightened to be of the size and strength of Olog-hai, a fierce race of trolls serving Sauron. Their troops are called "Half-Troll Warband" and "Half-Troll of Far Harad". [1] Closing at the end of the Third Age when Sauron was defeated, half-trolls too lost their powers and fell into the abyss.

A crossbreed between trolls and the orcs, the Half-Troll Marauders served as swordsmen for the Goblin faction.

Half-trolls were a type of enemy residing in the areas of Gondor and Anorein.

1. ^The Renaissance Troll: Half-Trolls.