The Ice-Biter Tribe is a tribe of rieklings found inside Cragwallow Cave. During the celebration at Cragwallow, the lute that Valding the Bard plays will attract the rieklings, resulting in the death of multiple workers.
The Icereach Coven are a group of witches who are based in the island fortress on Icereach, led by Mother Ciannait. During the rule of the Longhouse Emperor Leovic, they served as his advisors until they were driven out of Cyrodiil during Varen's Rebellion along with the rest of the Reachmen. They were further chased out of Skyrim, forcing them to return to their island home.
In recent times, they drew attention to themselves with the unnatural storms brewing on the Sea of Ghosts. The Nord forces sent to investigate quickly found that the Coven had regained strength and the patronage of an unknown benefactor.
The Imperial Legion is the main army of the Empire of Cyrodiil, or what remains of it. They are loyal to the one who sits on the Ruby Throne, which is currently Clivia Tharn, though Mannimarco is secretly the one from which their orders come. Another Tharn, Septima, is the Magus-General of the Imperial forces near High Rock.
During the Interregnum, the Empire fell into disarray and the Imperial Legion gradually lost control of its provinces. As a result, a large Imperial military presence can only be found in various camps throughout Cyrodiil.
The Invisible Web is a clan of Spiderkith that resides in Fargrave's Shambles. It consists of spider-like Daedra and an army of spiders of all shapes and sizes. The eastern section of the Shambles (known as Skein Row) is their lair and hunting ground. Thick webs cover every inch of their territory.
The Ironeye Tribe is a goblin tribe that have infested the dilapidated grounds of Black Drake Villa. They count a number of minotaurs among their ranks, including the large and powerful Kinras Ironeye.
The Iron Orcs are an isolated Orcish civilization native to the Dragontail Mountains of Craglorn. They are known for their stone worship and their savage brutality, and are based in the Nordic ruins of the Valley of Scars. They tame Welwas and Trolls as war beasts, and primarily use iron arms and armor. They are culturally separate from other Orcs, and possess their own language.