Dark Elves

"Long before the birth of light there was darkness, and from that darkness came the Dark Elves. Millennia ago the most ruthless of their kind, Malekith, sought to transform our universe back into one of eternal night. Such evil was blossomed through the power of the Aether, an ancient force of infinite destruction."

- Odin The Dark Elves, or Svartalfar, are the oldest known species in the universe, hailing from the obscure realm of Svartalfheim. They are mortal enemies to the Asgardians.

History
The Dark Elves are a proud, ancient race, their history extending centuries before the "Great Beginning" (Big Bang). Their civilization existed long before those of the other Nine Realms did, and they reigned absolute over the universe. When the other civilizations of the Nine Realms began to arise, the Dark Elves sought to return the universe to its former state of darkness, and began preparing to use the Aether, a superweapon engineered by their leader, the sorcerer Malekith. The Asgardians, led by their then-king Bor, fought a fierce war with the Dark Elves, eventually driving them back to Svartalfheim as Malekith attempted to use the Aether. In that final battle, with the Convergence approaching, the Dark Elves fought with all of their might, utilizing their advanced technology as well as their elite troops, the Kursed, to attempt to halt the Asgardian advance.

The Asgardians were able to triumph, however, launching an attack on Malekith and his bodyguards. During the struggle the Aether was lost to Malekith, taken by the Asgardians via the Bifrost. His plans ruined, Malekith launched a final, suicidal attack on the Asgardians, dropping the Dark Elf ships out of the sky in an effort to crush all beneath them. Malekith himself escaped the battle, along with dozens of his kin and his lieutenant, Algrim, who would later become one of the Kursed himself. The battle caused the utter destruction of the rest of the Dark Elves, leaving those that escaped aboard Malekith's ship as the only survivors.

Five thousand years later, as the Convergence neared again, Malekith attempted to use the Aether again. By this point, however, it had planted itself within the body of the human woman Jane Foster. Malekith led his kin in an attack on Asgard, where Thor had taken Jane. Using cloaking devices, Malekith's ship, along with a number of smaller ships, were able to launch a surprise attack on Asgard, using their nimbleness and durability to smash through the Asgardian defences, though two of the ships were destroyed by the Asgardians in the process. The final ship, with assistance from Algrim, now the last of the Kursed, managed to break through the Asgardian defenses and disgorge its complement of Dark Elf soldiers, along with Malekith himself. The Dark Elves engaged the Asgardian soldiers, both sides suffering heavy casualties as Malekith made for the chambers of Frigga. The Dark Elves were eventually driven away, bereft of their prize, losing three ships and dozens of soldiers in the process.

When Thor, Jane, and Loki came to Svartalfheim in order to trick Malekith into removing the Aether from Jane where it would be destroyed, a number of Dark Elves accompanied Malekith and Algrim out onto the field. In the ensuing fight, Loki and Thor killed all of the present Dark Elves, including Algrim, though seemingly at the cost of Loki's life. The rest went to Earth, where they could disperse the Aether to all nine realms and destroy the universe. The rest of the Dark Elves were killed in the ensuing battle, along with Malekith. They are most likely now extinct.

Technology
Dark Elf technology was very advanced, either matching or slightly surpassing the Asgardians. They possessed massive, black, T-shaped spaceships with red lights that could travel between the Nine Realms. Each ship could carry several smaller, nimbler "Harrow" craft that could function as troop transports or fighters, using their blade-shaped hulls and superior durability to ram enemy ships and fortifications. Their cloaking devices could render them invisible to any means of locating them, and could even conceal them from the all-seeing eyes of Asgard's guardian, Heimdall. They were also extremely durable, able to withstand projectiles from Asgardian weaponry to a point, and also able to smash through objects without any noticeable signs of damage. The Dark Elf Harrow craft's engines each contain a small black hole used as a propulsion source; the red glowing aperture at the ship's front allows it to "fall" along the direction of travel at very high speeds.

The Dark Elves also possessed energy weapons in a similar vein to the Chitauri, along with swords, shields, and grenades that generate miniature black holes that would absorb and crush anything caught in the blast radius before disappearing a few seconds later.

The Kursed
"You'll be the last of the Kursed." "Let my life be sacrificed. The same as our people." "You will become darkness, doomed to this existence until it consumes you. Until then, no power our enemies possess can stop you."

- Malekith and Algrim

The Dark Elves also possessed their own form of enhanced "super soldiers" known as the Kursed. These, tall, extremely muscular soldiers gained their abilities through the breaking of Kursed Stones, gaining immense strength and durability at the cost of being eventually consumed by darkness as the "curse" killed them. All of the previous Kursed soldiers died during the Dark Elves' final battle with the Asgardians five thousand years ago, until Algrim became the last Kursed soldier in order to forward Malekith's plans to gain the Aether.

Characteristic traits
Like many other races in the Nine Realms, the Dark Elves are humanoid with a more advanced body structure than that of humans. Like the Asgardians, the Dark Elves possess natural forms of superhuman strength, durability, speed, reflexes, and coordination. It is presumable that they have prolonged lifespans of at least 5,000 years, as such with most of the other races in the Nine Realms, as Malekith is said to have been at least 3,000 years old before his hibernation.

Before their homeworld was ravaged by war, it is unknown how or if Svartalfheim's environment attributed to the Dark Elves' physical capabilities.

Notable Dark Elves

 * Malekith
 * Algrim

Trivia
Although she is not mentioned in the film, Alflyse is the Queen of the Dark Elves in the non-canon comic Captain America & Thor: Avengers!.