The Dark elves were a race of elves that formed from darkness. Thousand of years ago, they tried to plunge the universe into darkness at the Convergence (where the Nine Realms align and passage to each one instantly is possible), but they went into hibernation after Thor's grandfather Bor defeated them and the Aether was locked underground. They remained asleep until the Aether was accidentally discovered by Jane Foster. The Dark Elves ambushed Asgard to get the Aether (which was in Jane Foster's body). The Dark Elves retreated to the Dark World, but Thor and Loki followed. Thor managed to find him and destroy the Aether and finally defeat Malekith and his army.