The Marvel Cinematic Universe has introduced powerful beings before, but none perhaps more mighty than the Kursed -- the army of mutated Dark Elves as seen in Thor: The Dark World. Given the timeline regarding such a deadly species, the Kursed are also technically the earliest examples of Super Soldiers in the MCU.
When it comes to the MCU's history, few of the franchise's primary incidents date further back than those that take place within the realm of Asgard, as presented in the Thor films. In this case, the early notable occurrence is the battle of the Asgardians against the Dark Elves, which took place 5,000 years before the events of The Dark World. The two armies declared war over the Aether -- a cosmic element birthed from the Reality Stone -- with the Dark Elf militia being commanded by Malekith and his general, Algrim the Strong. The fight ended with the Dark Elves being all but completely wiped out by the Asgardians, but by the present-day timeline of The Dark World, Algrim returns to seek revenge, harnessing the power of the Kurse Stone.
The Kurse Stone contains the power to physically transform any being that wields it; its gruesome metamorphosis becomes evident once Algrim has his hands on the artifact. As the film depicts, the stone upgrades the Dark Elf lieutenant with a fear-inducing appearance while also making him grow in size, strength and speed. Algrim takes on an advanced form, undergoing his new name, Kurse, as a reference to being the last of his kind. Before they were decimated, the Dark Elves utilized the Kurse Stone during the war so they too could hideously transform into more powerful beings. They dubbed themselves the Kursed.
Amounting to a sizable superhuman army, the Kursed appeared to be a frightening, impenetrable force, nearly overthrowing Asgard before being outnumbered. The sheer dominance of their artificial power alone was comparable to the likes of a Super Soldier -- as seen in the Captain America mythology -- with one glaring difference. Although Super Soldiers were juiced with new and substantial bodies, their minds remained relatively intact. On the opposite end of the spectrum, the Kursed in their prime were a combative and ferocious race. In surrendering themselves to the Kurse Stone, the Dark Elves were not just transforming their strength, but their humanity as well.
In this sense, the Kurse Stone operates similarly to the Super Soldier serum by improving physical prowess. And yet, since it destroys all moral inhibitions of its host, the Kurse Stone is actually far more dangerous. Whereas Super Soldiers usually question their actions based on patriotism, the Kursed behave solely on overbearing dominance. Given such a threatening magnitude of unsympathetic power, it's a relief that the Kursed were mostly wiped out during their battle with the Asgardians. Had that fashion of sheer brutality survived after 5,000 years, the Kursed could have thwarted nearly any force standing in their way.