Bred in Mordor by Sauron, the Olog-hai were an attempt to create immensely strong creatures that were intelligent enough to be used as troops. Ordinary Trolls were unsuitable - strong but stupid - and so, according to rumour, they were interbred with the variags, a cruel mannish race.

The result were the Olog-hai of Mordor; cunnig and immune to the effects of sunlight and smaller than other Trolls, they were sometimes mistaken for huge orcs by enemy soldiers.