In the era of the Marvel Cinematic Universe, there's no ancient deity more famous than Thor - Asgardian, Avenger, and God of Thunder. Actual Norsemen of antiquity, however, might be annoyed if they knew how little the Chris Hemsworth version of the character resembles the genuine Thor of Norse mythology. Though not every retelling of the Prose Edda and Poetic Edda agree about the details of the Odinson's life, they do make it clear that Jack Kirby and Stan Lee took several liberties when lifting their superheroic creation from Scandinavian lore.
It's true that the popularity of Thor in the pages of Marvel Comics, and later the MCU, has increased global awareness of Thor, Loki, and all Norse gods and myths, but unless one is willing to consult the original texts, they're not going to get the whole picture. After all, there are some pretty strange tales of Thor and the rest of the Aesir out there to peruse - and they sure don't look much like any of the adventures that have made it to the big screen thus far.
Thor's Actual Brothers Include Balder, Heimdall, And Tyr
Thor and Loki's close relationship in the Marvel Cinematic Universe is explained by the fact that they're one another's only sibling - that they know about, anyway. As it turns out, they're not even related to each other in the actual Norse mythology - but that doesn't mean that Thor is without brothers.
Most sources agree that Odin had at least four sons with various mothers - Thor, Balder, Vali, and Vidarr. Some other tellings mention a much longer list that includes names like Tyr, Hermod, and Heimdall, though it's possible that these individuals were only "sons of Odin" in the metaphorical sense.
You Don't Have To Be Worthy To Wield Mjölnir
If there’s one trait that defines Thor in both Marvel Comics and the MCU, it's worthiness. In order to wield the mighty hammer Mjölnir, one must prove oneself worthy of the power of Thor - and the list of individuals to have qualified is not very long. Even the God of Thunder himself struggled for a millennium before he had what it takes.
The Mjölnir (or Mjöllnir) of antiquity, however, had no such requirements. It was indeed a magic mallet, but anyone could pick it up - though actually using it involved skill and some additional equipment. On at least one occasion, Thor had his hammer taken by a giant, which is not something the MCU version has ever had to worry about. To be fair, the real Mjölnir did also come with some additional abilities - like the power to shrink down and fit inside Thor's pocket.
Mjölnir Is Only One Piece In Thor's Ensemble Of Magical Accessories
The Thor most of the world is familiar with doesn't need much to save the world - just his trusty hammer, Mjölnir. The God of Thunder that actual Norseman prayed to, however, had a significantly larger arsenal of magical wares.
In order to properly wield Mjölnir and have it return to his hand when he threw it, Thor had to wear a special pair of gloves called Jarnglofar. This was a result of another classic Loki prank that ended in the hammer being crafted with too short a handle.
To reach his peak effectiveness as a protector god, Thor also had to strap on a mystical belt known as Megingjörd, which was said to double his strength. It's an item that was briefly referenced by Happy Hogan in Spider-Man: Homecoming, but only as a throwaway gag.
Frost Giants Aren't All Actually Giant
Whether one is watching Thor on the big screen or reading about his adventures in the pages of Marvel Comics, they’re sure to run into a scene in which the God of Thunder takes on a horde of towering Frost Giants. Clashes between Thor and the Jotnar were certainly frequent occurrences in Norse mythology - but it's the height difference that the source material doesn't support.
Some of the more infamous Jotnar - like Ymir and Skrymir - were indeed excessively large, but most of them were the same size as Thor and his compatriots. This confusion has led to the translated word "giant" being understood as a skyscraper-sized individual, when it was originally meant to describe a diverse cadre of Earth gods closely interrelated with the denizens of Asgard.