Brief History: Marvel
Most well-known group of the many races/species that lives in/on the extra-dimensional planetoid of Asgard. The Asgardians, or Aesir, are technically not immortal gods, but extra-dimensional humanoids with both physical and magical properties. They are not immortal, but have incredibly vast lifespans (compared to humans) combined with regular consumption of golden apples of the cosmic tree of Yggdrasil to maintain their vitality. Hence even a "God" as old as Odin still retains vast physical strength.
Untold centuries ago, the Nine Worlds were created by Those who Sit On High in Shadow as a way of watching "lesser beings" who had dwelled below the 9 Worlds. In doing so, the Norse Gods were born, a group of beings who had been born in blood and battle in hopes they would evolve past themselves and become true rulers of man. Eventually they achieved this and their civilization began, eventually a battle broke out between two brothers of the King of Asgard known as Bor. At some point, the youngest brother, Odin succeeded in battle and imprisoned his older brother who was meant to be the next in line for the throne of Asgard. With his brother gone and his father following in battle with the Frost Giants, Odin became the High Father of Asgard and sought rule over both the 9 Worlds and Migard (Earth). As the years passed, Odin's wisdom grew stronger and he sought to understand more of the 9 Worlds but his curiosity lead to war with the Dark Gods, an off shoot of Asgard and war broke out between them and Asgard fell for the first time. After Thor aided his father in battle, Odin retook Asgard and banished the Dark Gods. Centuries passed and Asgard fell victim to Sutur of Muspelhiem, and in a final battle, Odin and Sutur were killed in battle and Asgard fell once again. However, they both returned alive and Odin return to rule the kingdom.
It was revealed that the Norse Gods and the Nine Worlds were caught in an endless cycle of death and rebirth, engineered by Those who sit on High in Shadow. Odin was the only one who knew this and kept it secret from his people.
Asgardian bodily tissue is much denser than that of humans, giving them great weight and immense strength. This is combined with an accelerated metabolism that provides enormous stamina and reserves of energy, as well as the capacity to heal rapidly from wounds and great resistance to disease. As the Asgardian culture prizes glory in battle above all things, most Asgardians are highly skilled fighters in hand to hand and (archaic) weapon-ed combat.
Though no Asgardian has been shown dying of old age, they can be killed. If they are killed in battle, their souls are taken to Valhalla, feast hall of Odin. If they die by other means outside of battle (even if murdered by another's hand), then their souls are condemned to the realm of Hela, Hel.
Magic forms a great part of Asgardian life. It is almost a daily aspect of it. However, although all Asgardians born with a capacity to wield magic, few (such as Frigga, Loki and the Enchantress) have set out to master it.
At one point, the Egyptian god, Seth sought to destroy Asgard and with Thor lost in Onslaught, he saw it as the perfect time to claim Asgard and end the cycle to reshape the kingdom to his rule. However, the Asgard rose and stopped Seth but in their weaken state, the Dark Gods returned and destroyed Asgard to reshape in their own image. Eventually, Thor returned and freed his people and Asgard returned to its wondrous state again. However, those times grew dark again as Surtur returned to Earth and Odin was once again lost and Thor took over as ruler. In was during this time that Loki had discovered the truth behind the endless cycle of death of Asgard and sought to reshape it in his own way. He created Ragnarok once more and devastated Asgard until Thor had discovered the truth and used the powers of the Rune Stones to end Loki's rule and break the endless cycle of Those who Sit above in Shadow for good.
After the destruction of Asgard and the Civil War had concluded Thor returned from the dead. Choosing an appropriate spot in the Oklahoma desert Thor re-created Asgard exactly as it was before Ragnarok. When the farmer that owned the barren land resented Thor putting a mystical land above the land he owned Thor offered to purchase the land, allowing him to enter Asgard's vaults and take whatever price that he deemed the land worth from the treasure stores. Asgard currently hovers above this spot in the Oklahoma desert.
During Siege, Asgard was invaded by Norman Osborn and the majority of his forces. As a result of the battle, Asgard was toppled and destroyed by the Sentry. Seeking to rebuild, Asgard's main kingdom was rebuilt over Avengers' Tower, as a true merging of gods and mortals on Earth protecting all those around them. Following this, the ancient alien gods known as The World-eaters returned, intending to consume Earth since Asgard was now part of the same kingdom as the Nine Worlds. With no way of knowing how to stop them, Thor brought his father back to life by destroying his casket and re-channeling the odinforce into it and the High Father was reborn to lead his people in a new age but not without a heavy heart as he felt Thor was meant to finally take over as leader and knowing that the next Ragnarok will be permanent.
Powers and Abilities
Asgardians possess the standard physical attributes of an Asgardian Male: Superhuman strength enabling him to lift at least 30 tons, superhuman speed far superior to that of the finest human athlete, stamina enabling him to perform at his absolute peak for at least 24 hours before even starting to tire, superhuman reflexes greater than a human's, superhuman durability that allows them to withstand powerful impact forces, extreme temperatures and pressures, falls from great heights, energy blasts and high caliber bullets without sustaining injury; and finally, Asgardians' agility is also superhuman. Asgardians also possesses a regenerative healing factor, being capable of healing from injuries such as slashes and puncture wounds in a matter of hours, and mending broken bone within the day. They can't however, regenerate missing limbs or organs without magical assistance. The Gods of Asgard are also granted certain mystical abilities that in the past have shown to get them the power to change their appearance, transform matter and wield a numerous amount of different energies. Though many Asgardian Gods/Goddess' have not shown the ability to wield any type of energy or shown any mystic abilities these powers are inherent to all of their race.