The Olog-Hai are a subspecies of Troll and one of the main types of enemies as well as one of the new classes introduced in Middle-earth: Shadow of War.
A significant difference between the Uruk and the Olog is the latter's larger size and distinct lack of pointy ears; rather the Olog's ears are small and less fleshed out. Another key difference is the lack of five digits on their feet. Therefore, they appear similar to Goblins, but larger in proportions.
The Olog-Hai reside from the Misty Mountains to Mordor, and are the only species of Troll not turned to stone by the light of the sun. Their presence alongside the Orcs (Goblins/Uruks/Orcs) typically manifests as armored soldiers or enforcers for smaller groups. They also work closely as master engineers alongside the Orc species known as Goblins, being able to create deadly weapons and powerful equipment, such as blasting powder. There exist cases of human-level intelligence, but the majority are more in favor of brawn over brains, thus they can be easily tricked. They often make use of Goblin-forged, or even scavenged armor, though most prefer not to wear clothes.
The Dark Lord Sauron has begun to breed Olog-hai for the war to come, serving many purposes as soldiers, guards, and escorts, with several earning their place among the Captains and Warchiefs, while few even manage to become powerful enough to be named Overlords of the fortresses dotting Mordor's landscape. They also provide support as siege beasts and gate-smashers.
The Olog's skin seems to vary in tone, in comparison to Uruks, being either pale yellow, orange yellow, grey blue, stone grey, reddish-bluish white, or even pale white.