Eldar

The Eldar are a race of elf-like humanoids. They are one of the most ancient and advanced races in the universe's history, though younger than the Necrons, C'tan and The Old Ones. Their armies usually have the advantages of speed and technology.
In the sense that Warhammer 40,000 races parallel the earlier Warhammer Fantasy game, the Eldar parallel the Elven race. In Warhammer 40,000 the Eldar are divided into three distinct groups with their own distinct armies: the Craftworld Eldar, who are similar to the High Elves, the Dark Eldar, who are similar to the Dark Elves and the Harlequins who would most closely resemble Wood Elf Wardancers from Warhammer Fantasy. The Exodites, who exist mainly in Warhammer 40,000 background material, are similar to the Wood Elves. The equivalences are only in very general thematic terms however, as the major details of the races' backgrounds differ greatly from their Fantasy counterparts.