Thor (2011)

Odin (Anthony Hopkins), king of Asgard, tells his two young sons Thor and Loki the story of how the Frost Giants of Jotunheim, led by king Laufey (Colm Feore), used the Casket of Ancient Winters in an attempt to plunge Earth into a new ice age. Many humans were turned into ice statues by the Casket's power. Odin and the Asgardian army fought and defeated the Frost Giants and drove them back to Jotunheim. Odin lost his right eye during the battle and made a peace treaty with Laufey, taking Casket of Ancient Winters to Odin's vault on Asgard so the Frost Giants could never attempt to conquer Earth or Asgard ever again. Odin tells Thor and Loki both of them were born to be kings and only one of them will ascend to the throne of Asgard. Odin eventually gives Thor the hammer Mjolnir.

In 2011, the Asgardians gather in the palace for God of Thunder Thor Odinson's (Chris Hemsworth) coronation, as Odin is ready to make Thor king. Thor's childhood friend, the beautiful Lady Sif (Jaimie Alexander), attends the coronation. Sif is a warrior who is in love with Thor, although Thor has not fallen in love with Sif. Thor's other friends the Warriors Three, Fandral, Volstagg, and Hogan also attend, as well as Thor's jealous brother Loki Odinson (Tom Hiddleston), God of Mischief, and Thor and Loki's mother Frigga (Rene Russo), queen of Asgard. Before Odin can officially crown Thor king, Frost Giants, secretly allowed into Asgard by the evil Loki, sneak into Odin's vault to retrieve the Casket of Ancient Winters, but Odin uses his magic staff Grungir to summon a suit of armor, the Destroyer, which uses its power to kill the Frost Giants. Thor arrogantly wants to wage war against Laufey and the Frost Giants as king of Asgard, but Odin tells him he is not yet king, angering Thor while Loki quietly watches, secretly pleased with himself for ruining Thor's coronation. Loki desires to rule Asgard but feels that Odin has always favored Thor instead of him.

Thor later tells Loki, Sif, and the Warriors Three they are going to Jotunheim to prevent the Frost Giants from making another attempt to steal the Casket of Ancient Winters. Bifrost gatekeeper Heimdall (Idris Elba) opens the Bifrost portal, transporting them to Jotunheim. The furious Laufey warns Thor that his actions will reignite the ancient war between the Asgardians and the Frost Giants. Laufey allows the group to leave Jotunheim in peace, but one of the Frost Giants taunts Thor, causing Thor to bash him with Mjolnir. Thor, Loki, Sif, and the Warriors Three battle the Frost Giants. One Frost Giant grabs Loki's wrist, and Loki's wrist turns blue before returning to it's regular color. Laufey summons a Jotun Beast to kill the group, but Thor defeats it. Odin rescues the group and they return to Asgard. Odin strips Thor of Mjolnir and his powers and banishes Thor to Earth for his reckless actions. Lady Sif and the Warriors Three learn that Loki told a guard to tell Odin they were going to Jotunheim.

Loki goes into the vault and picks up the Casket of Ancient Winters, which briefly causes his face to turn blue, making him realise he is actually a Frost Giant. Loki angrily questions Odin about the truth of his origins. Odin reveals that, in the aftermath of the battle on Jotunheim he went into Laufey's temple and found a small baby, Loki Laufeyson, abandoned and left to die. Odin used his powers to make Loki look like a regular Asgardian so Loki would never feel different or learn that he was really a Frost Giant. Loki angrily accuses Odin of favoring Thor all these years because he could never have a Frost Giant sitting on the throne of Asgard. Odin falls into the Odinsleep and, because Thor has been banished to Earth, it falls upon Loki to temporarily rule Asgard until Odin wakes up. On Earth, Thor meets and falls in love with Jane Foster (Natalie Portman). On Asgard, Lady Sif and the Warriors Three ask Loki to undo Thor's banishment, but Loki refuses, since Loki wants to permanently remain king and knows Thor is still a threat to his reign.

At one point, Loki travels to Jotunheim and uses his powers to prevent Heimdall from seeing or hearing him. Loki reveals to Laufey that he allowed the Frost Giants into Asgard during Thor's coronation. Loki tells Laufey he will conceal Laufey and a group of his soldiers, lead them into Odin's bedchamber and allow Laufey to kill Odin, after which Loki will return the Casket of Ancient Winters to Laufey. Heimdall later opens the Bifrost portal against Loki's orders, allowing Sif and the Warriors Three to go to Earth and bring Thor home to stop Loki. In retaliation, Loki uses the Casket of Ancient Winters to freeze Heimdall. Loki summons the Destroyer to go to Earth and kill Thor, Sif, and the Warriors Three. Thor, Sif, and the Warriors Three manage to defeat the Destroyer and return to Asgard to stop Loki. Thor earns Mjolnir and his powers back. Laufey attempts to kill Odin, but Loki betrays Laufey and kills Laufey by blasting him with Grungir. This makes Loki look like a hero in front of Frigga, but Thor arrives and reveals Loki's treachery to Frigga. Thor and Loki battle each other with Mjolnir and Grungir in the Bifrost observatory and on the Bifrost bridge. Loki tries to use the Bifrost to destroy Jotunheim and the Frost Giants, but Thor destroys part of the Bifrost bridge to prevent Jotunheim's destruction.

Odin arrives to save his sons, but Loki lets go of Grungir and falls through a portal in space. In the palace dining room, Frigga asks beautiful Lady Sif how Thor is doing. Sif painfully realises Thor is in love with the mortal Jane Foster and mourns for his brother Loki. Odin tells Thor he is proud of him, but Thor realises he is not ready to be king of Asgard yet. In a post credits scene on Earth, Nick Fury (Samuel L. Jackson) reveals the Tesseract to Eric Selvig. The Tesseract is a blue cube with the Infinity Space Stone inside of it. Loki, having survived his fall, magically prompts Eric to agree that the Tesseract and its powers are worth looking into.