First and foremost, I'm ruling out any misinformation of mine, because Norse mythology we know of today is a total mixture of different cultures. All of the creatures, paganic holiness and beliefs have been progressive lore which developed prior to the foundation of the Vikings. Which means, that the Germanic tribes that lived in Scandinavia, have started the notion of these gods way before the Norse, and the Vikings just continued on believing and crafting new myths, as an extension to what was known back then to them. In the modern-day world, this mythology is considered as Norse mythology completely with a slight reserve that it is not theirs as a whole, after all.
Besides, there are so many stories and names of gods and super-beings, it's just impossible for them to create such a profound religion for just a couple of centuries. There are back stories to all of it, and I'm not going to deal with it this time, I'll just tell the stories as they are and it's up to you to do extra research of name etymology, history, etc. Any further digression I make could be reasoned as conspiracy theory so we'll try to avoid doing so.
Since most, if not all of these gods are transferred through the ages as oral traditions, I'll put all the pieces of the puzzles together from various sources and just present the points of intersection between these myths. Let's tackle on!
Starting off with probably the most important of all gods in all of Scandinavia. Highest regards ever went to him, almost as powerful as a superior god in monotheistic religions. The catch is that he's confirmed to be a Germanic construction, as in Romanic mythology there's an almost exact equivalent called god Mercury. The connection is revealed in Tacitus' (Roman senator and one of the biggest historians) writing Germania.
Odin was incoherence with immoral attributes, seemingly unholy, is a bit of a contradiction to his holiness, because he was known for sorcery, frenzy, evilness from time to time and atrocity, however, on the other side, healing powers and oozing wisdom. In fact, he sought wisdom and knowledge at the extent that he pulled one of his eyeballs in the name of Mimir, probably a creature with most brain power and utmost wisdom.
Odin found his beheaded body after the Æsir-Vanir war. It's told that Odin later carries his head as Mimir whispers his secret knowledge to him. Mimir got his brain powers after drinking water from the Well of Urd, and he offered Odin draught water from the roots of Yggdrasil (Warcraft lore took this name for the ancient tree, as in history it's the cosmic binder of the 9 worlds in Norse mythology).
Odin's name is brought to the land-combating berserkers in the military formation of the Vikings. I mentioned them in one of the previous articles, and in the name of Odin they fought. Besides being the ruler of Asgard, Odin is a warmonger, maniacally leading to wars and that's why he was the igniter of close combat battles to the berserkers.
Modern-day recognition hasn't made Thor to slightly deteriorate. He's the famous one as of today since he's repeatedly mentioned in any superhero movie or tale. However, he's always depicted as a fun and cool guy, history begs to differ. He is the god of thunder, the protector of cosmos and defender of a stronghold of Asgard.
Thor is the son of Odin, and he's depicted in the Germanic culture as a sturdy, robust and brave warrior, a loyal advocate deriving his heroic aspects from his father Odin. Included in some ancient poetry, Thor is considered as the strongest entity of all gods and creatures. Except for his mighty red beard and eyes, he wore iron gloves and the mentionable belt of Megingjard.
However, the item he possessed with which he got his fame of today, is - you guessed it right - his hammer Mjöllnir or translated "lightning". The dwarf creations crafted this monstrosity, and it's believed by the Norse of then that whenever the weather was stormy with thunders, Thor must be swinging his hammer at foes, killing giants and demons while riding his chariot which is drawn by Tanngniost and Tanngrisnir, two huge phantom goats.
Readers who link things up pretty fast, or those pertaining wider knowledge on Thor than I am, the thunder resemblance is because Thor was regarded also as the god of agriculture and soil fertility. Being the cause of rain, along with his wife Sif who had blonde (golden) hair - which portrays grain, the two of them united together represented a fruitful year, once combined.
Just like Thor's hammer is illustrated in superhero movies as a grand hammer, that's how Loki role was played by a charismatic character making Loki favorable and quite a likable entity. Thor's hammer was scaled way off its true dimensions, and Loki's fraud-ish behavior masked by uncalled for pity that you feel at the end of the movie I won't name, neither spoil.
Truth be told, let's derive all the fake and just simply draw Loki as how he was conceived by Norse of the ancient centuries. Although not only that he was devilish, a playful spirit with a general purpose of causing damage, despair, and misfortune, he held the power of shapeshifting, which he inherited from his father giant and mother giantess.
Loki's true purpose remains vague, a very complex entity with enticing bearing hadn't had the clearest of destinies. In general, he remains and is held responsible for the deaths of numerous gods during Ragnarok, the last battle between gods which later resulted as the incentive of a new order. Thor and Loki's close bonding is also a hugely foggy relation.
Namely, in some scripts, Loki and Thor had quarrels and disagreement, Loki feared the hammer of Thor's and its intimidating strength, however in other sources Loki and Thor had formed a fellowship to bring back the stolen Mjolnir from Prymr, in one legend it says that he did so to extort he gods to give him Freyja, the goddess of love.
For what she's prominent and eminent is that she's the goddess of fertility, love, beauty and is a seeker of pleasure and the unknown. Her alleged ability was that she took seer sight and vision, that she could sew the destiny of a subject as well as his fortune. The abilities she inherited are from "Vala" a female oracle, a prophet in the Norse mythology.
She had been changing people's desire and destiny, therefore Freya resembles the attitude of a cat. You know, the superstitious - black cat crossing your path and all that. Besides these enormous pulling strings, Freya could choose half of the warriors fallen in battle and lead them to an afterlife realm of Folkvang.
The other half is guided by the Valkyries, creates which we will later describe. The parallel Germanic entity to Freya, or specifically the Vala she has taken powers from is the Germanic pantheons, two gods who symbolize a warrior chieftain and his oracle wife. The Germanic tribes would believe that the chieftain leads to subsequent battles, while his wife would predict the outcome of it with her magic.
Freya's twin brother is Freyr, not to be mixed up, these are two different entities.
Of the two largest tribes, Æsir and Vanir, Freyr belonged to the other one, opposing to the gods we've introduced so far. These two tribes go in spite of the other, and Freyr is portrayed as a muscular man with facial hair nowadays pretty popular because it symbolizes masculinity. In some articles from us you can try and steal his look, but don't think he's a hippie, since there are portraits which he looks like a farmer with his boar, and of all the deities he depicts the most sexual and ecological arsenals.
That being said, him and especially his boar regard fertile harvests, wealth and peace. The worship of Freyr would be brought up during marriage and its rituals back in the day, thankfulness after a plentiful harvest, and as a sign of appreciation, worshipers would slay a boar as a sacrifice in favor to Freyr.
Freyr used to travel in his chariot just like Thor, however, his carriage was towed by boars, of course. Germanic priests would practice this legend and in order to mimic his holiness, they were used to travel by chariots as well, like they are the children of Freyr.
Out of historic reach, Freyr was linked to elves, as their ruler since he lived in Alfheim. There were beliefs that he was a claimed king with a wealthy lifestyle, however, these are unknown allegations, unofficial, just as him pertaining a foldable ship, which had the control of winds always going to its advantage to blow in its favorable way.
Can almost be described as a god of all gods, not Odin. Just like other tribal mythologies known of today, Ymir was an ancestor to all the gods, fantastic creatures and entities. He's more like an abstract entity, not embodied as a half human, half god, but a being that was first ever to be created, long before planet Earth.
Ymir came to existence after a combination of ice from Nilfheim and the heat of Muspelheim, two of nine worlds of the Norse mythology. His genesis made him a hermaphrodite, so he made the first generation of gods, both male, and female, and he's the vortex on top, the primal cause to all consequences and repercussions. All known mythical beings without an embodied older generation are considered to come from Ymir.
The "family" tree goes like this: after the creation of Ymir, Buri was yet to exist, and Buri had a son Bor, who married Bestla, one of Ymir's offsprings, and from their congregation, three sons were given godlike life - Ve, Vili and our favorite Odin. Ymir's death was related to his confrontation to the Norse gods, where he died in front of these 3 male children.
Odin was responsible for the making of Earth, where from the carcass of Ymir, he transformed his bones to become rocks and mountains, his blood being the seas and oceans, afterward, his hair morphed into trees and grass, his skull became the sky, Ymir's brain formed clouds, and his eyebrows were the middle realm Midgard.
Extra note regarding gods
Focal points indicate that these gods were the most mentionable ones, there's umpteen of them, descendants of the cited, who more or less had the same symbolic value. I just put the emphasis on the first generations of gods and their genesis.
Residing in the previously mentioned Alfheim, which alleged king was god Freyr, elves were tall and skinny demi-gods with white skin and it's told that they are more beautiful than the sun. Elves didn't take part in many human happenings, they kept away from them, only if there's a reason for their operation, either causing or curing illnesses.
On the moral aspect, depending on the elf as an individual, there were good and bad elves, they didn't have a distinct gender like humans, but the general division was in two groups Dökkálfar and Ljósálfar. Roughly translated to English language and spirit, Dark Elves and Light Elves, probably each respectively implying to their temperament.
Some historians say that the notion of Elves is a bunch of rubbish, that they are just dwarves and that they couldn't be segregated from the rest.
Svartalheim, the place where Dark Elves allegedly lived, where Dwarves also lived, thus the dispute of Elves being Dwarves started. It's a common misconception that Dwarves are short entities, but literally translated from the original scripts, they were just "lesser" beings than the other. That's why they are portrayed as stubby since for the general public it couldn't be explained better.
By legend, it's believed that Dwarves lived beneath the land, underground constructions of mine and forges, the so-called Svartalheim. That's why smithing is related to be the best suitable occupation of Dwarves.
They are responsible for creating Thor's almighty Mjollnir, Freyr's foldable ship that can adjust the wind its favor and ultimately, Odin's ring and sword - Draupnir and Gungnir. In general, judging Dwarves by their everyday routine and attitude - they were wise, skilled and held magic powers.
Jotnar - Giants
Usually considered as giants, they are oddly defined because it roughly translated meaning that they're huge in appearance. However, humans and giants were the same sizes, scaling them physically.
They were always at war with the gods, both the Aesir and Vanir side, many of these Norse gods represented their giant alike, one or more of them. Giants are described by the gods as devourers and spirits of the darkness and cold.
Jotun's are Hel, the goddess of the underworld and Ymir, who after all was the first being in all of Norse mythology, already explained before.
Valkyries are also common in our languages of today, the global public having a bit of knowledge of their existence, however not quite, apart from the classical composition we listen as music. They're portrayed as riders, riding horses through the air, kind of like the riders of the apocalypse.
Valkyries were Odin's spirits who carried the fallen and deceased to Valhalla, the hall known in Norse mythology for "storing" the dead. They were female riders, maidens more like, and it's not very clear whether they had good intentions of being living caskets.
Because not only that they transfer the corpse to Valhalla, but before the warriors die in battle, the Valkyries were the ones choosing who'll live or not, so the destiny and outcome of an individual entity in battle were decided by them, which seems a bit of a disturbing ability.
Since the Norse main vehicle and avenues were watery ones, Kraken was the beast of the sea, often described as an octopus or crab, all-in-all, being an inhabitant of the sea - that's what's for sure. It's vague which was it because all the creatures resembled a mixture of animals, but not quite the concrete idea and form of the original animal, kind of a derivative of it.
Kraken was frequently mistaken for an island, looking like a surface of rescue to the Norse who were sailing at times, hopefully looking for a shore to settle, only proven to be a dormant Kraken waiting for its prey. Kraken's measurement was something like a mile in length so that it really confuses the sailors.
When the naval boats establish the Kraken would release its tentacles and pull everything it touches downwards to the deep sea for consuming! It was a rarity to be seen because the Kraken usually lives in deep water.
There's a lot to it regarding gods and creatures of the Norse mythology, however, it's paganic essence doesn't give it vast difference between them, as well as stories and wars, because the Middle Age Norse weren't such clever and developed people as we're aware of it today, so repetition and similarities could be found between most gods, wars and fantastic formations.
I have just pointed out those which we heard of, but don't actually know what the rendition of them was to the Scandinavian people back then. Hopefully, I cleared out some uncertainty regarding some, because I wasn't as educated as before as I am now after I did a thorough research of their mythology. Like I said, a lot of parallel characters derived from their Germanic predecessors and most of these facts rely on legends.