For all intents and purposes, Loki has always been considered the perfect foil to Thor; however, another enemy by the name of Malekith often gets overlooked. Given how deep and rich the history between the two foster brothers has always been in Marvel Comics lore, it's understandable that Thor and Loki make great foils to one another. However, Malekith may be better suited to match wits with the God of Thunder than even the God of Mischief and readers may already be familiar with this villain if they previously saw the movie, Thor: The Dark World.
Admittedly, suggesting that Malekith, of all people, could be Thor's greatest foe may sound ludicrous to anyone who actually saw Thor: The Dark World without knowing the character's comic background. With all due respect to Christopher Eccleston (who, acting-wise, truly did the best that he could do with a character who wasn't very well written), most audiences will agree that not only was Malekith dull as a villain, he ranks among the worst MCU villains in what most many would easily consider to be the worst Thor movie in the MCU.
However, the War of the Realms arc from Jason Aaron and Russell Dauterman showcased Malekith at his fullest potential. More than just a foil, Malekith is portrayed as the perfect antithesis to Thor, and showcases some of Mr. Odinson's own qualities. One of those similarities are present in Thor #15 by Aaron and Michael Del Mundo, which concludes with the reveal that Malekith's own personal Hel is living without war.
For Malekith, he struggles to exist without a conflict to maintain, or perhaps even create. Similarly, Thor has often been characterized as such during his youth. Both men are effectively vicious in battle and born as honorable warrior princes, but the distinction is that Malekith takes delight in taking lives, even giggling as he massacres innocent people. Unlike Thor's royal upbringing, Malekith came from nothing, forced into a war he never started, thus also being born from violence without a proper code to draw a line for where enough is enough. His lack of morality in regards to violence alongside a sneaky, crafty personality makes Malekith incredibly compelling.
But, Malekith's biggest problem is that Loki exists. Loki bears the same lack of morality, the same mischievous attitude, and the same disturbing glee in violence. But the reason why Loki tends to get a bigger spotlight is because the brotherly bond between he and Thor offers far more intrigue, complexity, and storytelling potential. As a result, Malekith gets overshadowed and, as a result, often cast to the sidelines in both the comics and the movies. Which is a shame because if not for Loki, Thor's most interesting foil would easily be Malekith.
