Hela is a major antagonist of the Marvel Cinematic Universe, appearing as the main antagonist of Thor: Ragnarok. She is the first born daughter of Odin and the elder sister of Thor and Loki Laufeyson who is bent on taking over Asgard with her own army of Berserkers at her side and rebuilding it in her own image.
Hela started out as the firstborn child and sole daughter to Odin and Frigga. She served her father as an executioner and leader of the Einherjar in Odin's plot to conquer the Nine Realms. However, as the years go by, Hela start to develop her own ambitions in overthrowing her father and taking control of Asgard to herself. Having noticed his daughter's ambitions as well her warmongering behavior, Odin was forced to fight Hela and defeat her by banishing her to a realm called Hel, where his life force would be the only lock to keep her from escaping. Hela also tried to break free from Hel, which prompted Odin to send female Asgardian warriors called the Valkyries to stop her. The plan was a pyrrhic success, though it was at the cost of all the Valkyries, except for one.
Odin then proceeded to write out Hela from all of Asgardian history, even replacing the murals of her conquests with those of his other children.
Several years following the deaths of Frigga, Malekith and the Dark Elves, Thor battled against the fire demon Surtur, who foretells him of an event called Ragnarok that will destroy all of the Asgardians once his crown is united with the Eternal Flame within the city. Undaunted, Thor defeats Surtur and takes his crown, believing that he has averted Ragnarok.
However, Odin dies of old age after being found by Thor and Loki in Norway, but not before he tells them about the existence of Hela to them. Following Odin's death, Hela was able to escape from Hel through a portal-like gateway, musing that she would have liked to see her father die in which during their humorous encounter that when Thor introduces himself as her sibling, much to her shock in which she replied that he does not resemble Odin after all. When Loki proposed a truce, she sarcastically stated he sounded more like Odin. Forgoing all civilness, Hela then demanding her brothers to bow down before her and acknowledge her as their new queen. Thor and Loki defiantly refuse before the former throws his powerful hammer (the Mjølnir) at Hela, but unfortunately, she catches the hammer (in which the hammer was first wielded by her) and destroys it instantly with her bare hands before adjusting her headdress. A shocked Thor and Loki then attempt to escape to the Bifrost Bridge, but Hela pursues them and easily throws both of them out into space, leaving them to crash-land at a nearby planet named Sakaar (ruled by the notorious Grandmaster).
With both Thor and Loki banished, Hela took the opportunity to take over Asgard by eliminating the Einherjar (the elite army of Asgard) along with the Warriors Three (Volstagg, Fandrall, and Hogun) and eventually appointed a downtrodden Asgardian named Skurge to serve as her Executioner after the latter spared him upon her arrival in Asgard in which she killed Volstagg and Fandrall with ease for resisting her. Upon destroying the remaining army and with Asgard left defenseless, Hela then swiftly assumed the throne and destroyed the murals that Odin created which she described it as "lies" upon seeing within its murals that depicted peace treaties, festivities and exchange of gold and goblets; which its destruction revealed several of its darker murals that foretold her history before proceeding towards Odin's Vault with Skurge in which she discovered several artifacts stored in there as she declared the Infinity Gauntlet "fake", the Casket of Ancient Winters "a useless object", viewed Surtur's crown as 'smaller than she thought', became interested in the Tesseract but proclaimed the Eternal Flame the greatest of all. She smashed through the floor to the mausoleum underneath while wielding the Eternal Flame as she demonstrated to Skurge her true powers before descending down and used the Eternal Flame to resurrect her dead pet Fenris Wolf and her own army (known as the Berserkers) to cement her new role as Queen of Asgard.
With her subjugation of Asgard complete, Hela plans to use the Bifrost Bridge to expand the Asgardian empire through the universe, but Hemidall (the sentry of the Bifrost Bridge who was banished earlier by Loki) secretly returns as he covertly steals the sword controlling the bridge rendering it useless before hiding away with the rest of the Asgardian citizens to form a resistance against Hela's reign. A furious Hela then orders Skurge along with her troops to take down the resistance so that she can use Hemidall's sword to activate the bridge and proceed with her plans.
Eventually, Hela, Skurge and the Berserkers manage to discover the location of the Asgardian resistance with an information from a Asgardian civilian who exposed the location in which he revealed that the resistance took refuge on an old fortress within Asgard after Hela coldly ordered Skurge with a threat to execute a young and innocent Asgardian woman and upon hearing the plea of the civilian which led her to promptly convince Skurge to spare the woman.
Using the information that she gained from the Asgardian civilian, Hela and Skurge along with the Berserkers then begin their assault on the old fortress (by tearing down the ancient gate with her spikes) where Heimdall is hiding with the Asgardian civilians but the echo from Asgard's throne room that was sounded by Thor's hammering of an iron staff prompted her to return and confront him in which she was surprised that Thor managed to survive from their encounter in the Bifrost Bridge while Thor sarcastically stating of her actions by tearing down the murals as "redecorating" which he discovered the now revealed darker murals upon his arrival earlier while Hela replied that was "father's solution to cover it up" then demanded Thor to leave the throne but he refused which led to engaging in a fight with him, thereafter. This distraction also allowed Heimdall to evacuate the Asgardian civilians from the old fortress and led them to return to Asgard through the Bifrost Bridge only to be cut off from behind by Skurge and the Berserker army and in front by the enormous Fenris as both fronts began to attack them; However, the battle's tide is turned when Loki returned after defeating the Grandmaster's forcesand escaping Sakaar (with the help from the Hulk and several gladiators) on one of the Grandmaster's giant ships. It also turns out that one of the gladiators named 142 happens to be the sole Valkyrie who previously survived Hela's attack during her previous attempted escape from Hel. The Hulk and 142 then proceed to fight against Fenris, Skurge, and the Berserkers while Loki and the gladiators evacuated the remaining Asgardians on the ship.
With the defeat of Fenris and the Berserker army faltering, the duel between Thor and Hela continues to intensify, but he loses an eye and receives a vision from Odin that only Ragnarok can defeat Hela. It was then Thor realized that the true meaning of Asgard meant for protecting its citizens, not its land. Deciding to let Surtur bring about Ragnarok, Thor, 142 and the Hulk distract Hela while Loki takes Surtur's crown and unites it with the Eternal Flame, causing Surtur to be reborn as he eventually engulfed the portion of Asgard. Realizing that she's been distracted and witnessing the heroes and the remaining Asgardians escaping on the giant ship, an angry Hela attempts to stop them by pinning the ship with her spikes, but a repentant Skurge sacrifices himself to allow their escape by taking down several Bersekers (who were attempting to board the ship and attack the Asgardian citizens) before being stabbed to death by Hela with her throwing knives. Being left at the mercy of Surtur, a terrified Hela is forced to watch as Surtur proceeded to destroy all of Asgard despite her efforts to destroy Surtur by impaling the fire demon with a multitude of spikes, and she is ultimately finished by Surtur upon being struck on the tip of his mighty flaming sword down upon her, causing her to disappear in a blast of green energy, seemingly killing her for good, and her remaining Berserkers are incinerated to their deaths in the process.
With Asgard destroyed and Hela along with her forces vanquished, Thor (taking over as the new King of the Asgardians) decides to build a new Asgard for his fellow people on Earth.