Dark elves have appeared in many fantasy settings. Typically, they have blue or black skin which immediately differentiates them from traditional elves. In most settings, dark elves are at least somewhat evil or corrupt in some manner.
Dark Elves are Innoruuk's corrupted version of Norrath's elven population. They refer to themselves as the Teir`Dal, devoting their lives to Innoruuk, the Prince of Hate, and embark on a journey to spread hate and cruelty. Unlike the Ogres and Trolls though, Dark Elves are highly intelligent. Dark Elves reside in the underground city of Neriak where they are trained to exterminate all other races. Neriak produces casters of all types (wizards, magicians, enchanters), but necromancers are held in the highest regard. Other Dark Elves train to become warriors, shadow knights, clerics, and rogues. They do tolerate Ogres and Trolls for their devotion to hate and fear, but simply use these often dimwitted mastadons as tools for achieving their own goals. Dark Elves realize that their ways are not accepted by most other races throughout Norrath, and will often perform tasks in order to raise their faction enough to be tolerated in larger cities such as Freeport. All Dark Elves are born with ultravision which allows them to see as clearly in the dark as they do during the day. They all have the ability to Hide, and they can wear small or medium armor.
The Elder Scrolls
The Dark Elves (Dunmer in their native tongue) descended from the Chimer, a sect of Altmeri dissidents that left Summerset Isle in exile and settled in Morrowind. All Dunmer are dark-skinned and have red eyes. This is the after-effect of the powerful curse that turned all Chimer into Dunmer in the first place. Native Dunmer speak with a distinct, raspy voice; the result of the many ash storms that roam the island of Vvardenfell.
Dunmer, like other types of Mer, are "conditionally fertile", meaning they only conceive when population pressure is low. The Dunmer political system is complicated, and broken up into multiple factions. Native-born Dunmer tend to be distrustful and disdainful of other races; escpecially beast-races, such as Argonians and Khajiit, whom they often enslave. Recently, slavery have become abolished and slaves are gradually being freed.
After Morrowind's absorption into the Cyrodiilic Empire, some Dunmer have embraced Imperial ways, most notably House Hlaalu, the most opportunistic and economically dominant of the Great Houses.