Who he is: Algrim, a.k.a. Kurse
His power: As a Dark Elf, Algrim has extremely long life, and also possesses the enhanced strength and speed of an Elf. However, once he transforms into Kurse, Algrim becomes one of the strongest and most resilient creatures in all of the nine realms, though at the cost of death a short while after the transformation.
His story: Algrim serves as Malekith’s second-in-command in Thor: The Dark World, and in the pre-credits sequence, goes into hibernation for 5,000 years before waking again once the Aether possesses Jane Foster and the Convergence (a mystical lining-up of portals between all of the nine realms) is impending. Upon waking, Algrim volunteers to sacrifice himself by using a Kursed Stone, which will transform him into a nearly indestructible creature for a short period. Malekith hides a Stone in Algrim’s stomach, and the Dark Elf allows himself to be captured by the Asgardians and placed in their dungeon. He then crushes the Stone and transforms, destroying the dungeon, freeing the prisoners, and allowing Malekith to enter the city. After killing Frigga, Kurse and Malekith escape, until they are offered Jane Foster by Loki, and Malekith draws the Aether out of her and into himself. Malekith then leaves, but in the ensuing fight, Kurse seemingly kills Loki and then is killed himself when Loki activates the black-hole grenades on Kurse’s belt, weapons that detonate and essentially suck all nearby matter into their infinitesimal void.
Played by: Adewale Akinnuoye-Agbaje
Currently, Algrim/Kurse is: R.I.P.
Where will we see him next? He’s gone for good.