Fomori (singular "fomor") are an Irish Celtic subspecies of the troll. They are a little weaker than normal trolls and have no dermal armor. Like many celts they have a higher number of magicians in their ranks. Their form is considered by many to be more aesthetically pleasing than common trolls and orks.
Other than being trolls, fomori are not related to the similarly named fomóraig (HMHVV II infected trolls).