It's often said that a superhero is only as good as their Rogues gallery, and much to his credit, the God of Thunder is no exception. Here's an ordered list of the most notorious, deadly, evil, re-occuring, and just down right mean characters to ever match metal with the Mighty Thor.
Thor's foster brother and the Norse God of Mischief, Loki deserves the top spot as Thor's seminal arch-enemy. The interesting thing about their relationship is that, though on some level it's a battle to the death, these two actually love each other. And what better way of off setting Thor's nobility, physical power, and moral assurance than with Loki's impish manipulation, sorcery, and mercuriality? Loki's brilliance is in his complexity. One can never be too sure what his motivations actually are, whether they be truly malevolent or merely an extension of his mischievous nature. Furthermore, Loki's is a classic tragic figure, doomed to be clouded and undone by his terrible envy of his foster-brother Thor. And, ironically the only thing that's stayed Thor hand (or hammer rather) from crushing Loki long ago, is that Thor genuinely cares for his brother and considers himself partly responsible for Loki's decent into evil when they were both Asgardian youths.
Jormungand, happens to be one of Loki's progeny: no surprise the prophesy of Ragnarok finds Thor and the Midgard Serpent slaying one another. Jormungand spends most of its time coiled around Midgard (Earth) and pops his serpentine head up from time to time with a single motivation in mind: devour the Thunder God. What makes Jormugand such a threat isn't just that he's probably one of Thor's most powerful and deadly adversaries, it's that Thor knows that this is the monster that will eventually be his end.
Hey look, another one of Loki's kids. This time it's his daughter, Hela the Goddess of Death and the Norse land of the dead, Hel. One of Thor's more malicious and notorious villains, Hela once placed a curse on the Thunder God that found his bones as brittle as kindling and doomed never to heal, along with making it so even death wouldn't relieve the pain. Hela covets nothing more than to claim the soul of Odin's favorite son for herself, rendering him a highly prized slave in her already ghastly collection.
Possibly Thor's most powerful foe, Surtur is to Fire Demon's what the Midgard Serpent is to boa constrictors. For the Asgardian he's the ultimate destroyer (not to be confused with the actual Destroyer of course.) Every time Thor's went up against tall, red, and angry, he's been lucky enough to barely escape with his immortal life in tact. Surtur's not so much a villian as a catastrophic force of nature, and if he ever gets his hands on the Twilight Sword, his colossal reality altering blade, it's destined to spell the end of Existence itself. Though he's only #4 on this list of villains for Thor, he's #1 on the list of threats to all of Asgard.
Not so much a character as a weapon of mass destruction, the Destroyer is a mystical suit of armor, created and enchanted by Odin himself to eventually do battle with the near-infinitely powerful space gods, the Celestials. It is indestructible by conventional means and powerful enough--by the use of its disentigrator beam--to extirpate from existence anything it sets its sights on. Instead of being worn like your typical suit of armor, the prospective user inhabits the Destroyer with his or her soul/spirit, and animates it for whatever destructive aim they may have. And, in this fashion, there have been those odd ocassions that have seen the armor used for constructive means, but most often the Destroyer has been used against Thor, each time almost sending the Thunder God to an early grave--once doing just that. Whether inhabited by Loki or Aunt May, when the Destroyer comes on the scene, Thor has to pull out all the stops in his godly arsenal to decommission it. And that's puts him in the top 5.
Every hero needs his fall guy, and in so many ways, Ulik is Thor's. And, while this rage-filled hairball by may often get used as Thor's heavy bag more often than not, he's still one of Thor's greatest threats. Ulik is the mightiest of all the Asgardian rock trolls and one of the greatest warriors in all the 9 worlds, and he's one of the few denizens of those 9 worlds that nearly rivals Thor's own legendary strength. Ironically, it's the fact that Ulik's usually on the losing end of their fights that makes him so dangerous: Ulik's wanted to crush the Thunder God since both of them were practically pubescent, and he hasn't suceeded despite centuries of failed attempts. Ulik just keeps coming back for more, and his persistence alone gives him the number 6 spot.
Malekith is the most well-known and infamous denizen of Svartalheim, home of the dark elves, and there are more than a few reasons why Malekith rates this high. He's every bit the sorcerer and brilliant schemer as Loki is, and he was the treacherous mastermind behind the Surtur Saga, one of Thor's greatest, most fan-beloved adventures to date, and he still causing universal level discord as the architect of the recent War of the Realms. To top it all off, with the release of Thor: the Dark World, Malekith joins a very short list of Marvel villains to be represented on the big screen.
They say that love is a many splendored thing... and that it can also get you killed! Just ask Amora, the Enchantress; she's as deadly as she is beautiful, and she's had her heart set on Thor's since they were both Asgardian pups. Unfortunately, rather than court Thor the ol' fashioned way, Amora has been known to stoop to any length to seduce her beloved, including the use of mystical enchantments to usurp the Thunder God's will or allying herself with villianous undesireables on both Asgard and Earth. Amora is one of the most powerful sorcerers in all of Asgard, surpassed only by the likes of Odin, Loki, Karnilla, and a select few others. And while her vast magical abilities make her incredibly threatening as an adversary, her frequently obsessive willingness to do anything to steal Thor's love--even if it means killing him to do it--is what puts her in the top 10.
Gorr, the God Butcher is one of Thor's most recent villains whose sole purpose in life is to destroy all gods across the universe, believing them to be inherently cruel, capricious, and illegitimate. Armed with the mysterious Necroblade--a weapon that commands ancient, ebon energies which put Gorr on par with the likes of Galactus--and an unyielding resentment for all things godly. Apparently a boogeyman whose haunted Thor across the eons, Gorr was able to hurt Thor in a way perhaps no other enemy has: Gorr was able to convince Thor to doubt his own legitimacy. It was Gorr's insistence that no gods are worthy that crept into Thor's own mind and rendered him unworthy of wielding his fabled hammer, Mjolnir.
Skurge got his monicker of Executioner for being particularly efficient and cruel at dispathing giants, trolls, and other enemies of Asgard on the battlfield. And though the Executioner was an Asgardian, he was often possessed by jealous rage because of Amora's love for Thor. Amora frequently took advantage of Skurge's adoration for her, and frequently manipulated the Executioner into trying to execute the Thunder God. With his physical might, feral battle-savy, and his Bloodaxe--a weapon capable of cleaving almost anything, including the fabric of reality itself, and nearly the equal of Mjolnir--Skurge always gave Thor the fight of his immortal life. Though classically considered a villian, in the last moments of his immortality, Skurge sacrificed himself against Hela's undead forces in order to save the lives of others, thus earning himself a place in Valhalla. He may have died a hero, but the Executioner is imposing and vicious enough to still makes it into the top 10.
Absorbing Man is the first cad on the list who hails from Midgard (i.e. Earth). Low-level hood Carl "Crusher" Creel was slipped a magical Asgardian mickey finn by Loki, and gained the powers to absorb the physical properties or energy of anything he comes in contact with. Calling himself the Absorbing Man, Creel is one of the most powerful Earth based villians, and, he's locked horns with Thor on more than a few occasions. Creels powers even allow him to absorb the power and properties of Thor's hammer Mjolnir, making him particularly deadly. It's the nature of his abilities that put him as high as the number 11 foe, and he might be higher, but Creel is incredibly dim-witted, and his own stupidity is a rather conspicuous Achilles heal.
In terms of raw brawn and sheer indestructibility, it doesn't get more terrifying than Kurse. Originally the dark elf Algrim the strong--whose vast preternatural muscle already made him one of the strongest beings in all of the nine realms--made the mistake of following the treacherous Malekith the Dark Elf. Betrayed by the his former master, his already fantastic strength cosmically supplemented by the the power of the Beyonder, Kurse is a physical powerhouse filled with mindless rage. In terms of raw physical power Kurse nearly tops the list of Thor villains, but despite his fearsome demeanor and incalculable strength, Kurse only finds himself at the number 12 spot because his limited intellect and the simple emotional desires that motivate him curb what larger destruction he might otherwise be capable of.
The cosmic catastrophe rounding off the top fifteen's hatred is only dwarfed by his mammoth power. Mangog is composed of "a billion, billion beings" who were all destroyed by Odin, and he'd love nothing more than to see Odin, Thor, and the rest of the Aesir reduced to a cinder. The vast physical, mystic, and cosmic forces under his command are so great, he's even a threat to the Allfather himself. Thor and Odin have never failed to put a stop to Mangogs trail of destruction when it manifests, but it always takes every resource and ounce of will they have at their disposal to do it. Mangog's gargantuan power level and utter hatred for all things Asgardian make him Thor's number 14 villian at least. Mangog might be placed higher on the list, but he has relatively fewer major appearances compared to some of the other villains on the list.
I just think it's cool that Thor has his very own personal Kang, the Conqueror. I mean really, it's just good when Marvel has a time traveling character that's not Kang related. And he stands out as a Thor antagonist because his powers and personality are relatively unconventional. He's a mad scientist which are always interesting and relatively underrepresented with Thor rogues, and his time traveling ability allows him to pluck just about any Thor adversary you can think of out of the time stream. And you've got to beware any villain who can strike you at your worst moment, over and over again. If you ask me Zarrko is severely under used. He needs a makeover an another appearance.
She's worth a mention. She was the avatar or vessel for Skadi, who apparently was to the Serpent what Thor is to Odin. The only reason she's at the very end of the list is that technically She and Thor never engaged one another in combat.
