Thor: Ragnarok

Two years after the Battle of Sokovia,[a] Thor is imprisoned by the fire demon Surtur, who reveals that Thor's father Odin is no longer on Asgard. He explains that the realm will soon be destroyed during the prophesied apocalypse Ragnarök, once Surtur unites his crown with the Eternal Flame that burns in Odin's vault. Thor frees himself, defeats Surtur, and takes his crown, believing he has prevented Ragnarök. Thor returns to Asgard to find Heimdall gone and his estranged brother Loki posing as Odin. He forces Loki to help find their father, who Loki put a spell on after his presumed sacrifice years before.

With directions from Stephen Strange, they find Odin in Norway. Unpossessed, Odin explains that he is dying, Ragnarök is imminent despite Thor's efforts, and his death will free his firstborn child, Hela, from Hel, a prison she was sealed in long ago. Hela, a sibling Thor and Loki did not know existed, was the leader of Asgard's armies and conquered the Nine Realms with Odin, but he imprisoned her and wrote her out of history after she became too bloodthirsty and did not share his views on peace.

Odin dies and Hela appears, destroying Thor's hammer Mjolnir. She pursues the two as they attempt to flee through the Bifröst Bridge, knocking them out into space. Arriving in Asgard, Hela defeats its army, slays the Warriors Three, and resurrects the ancient dead who once fought with her, including her giant wolf Fenris. She appoints the Asgardian Skurge as her executioner. Hela plans to use the Bifröst to expand Asgard's empire, but Heimdall takes the sword that controls the Bifröst.

Meanwhile, Thor crash-lands on Sakaar, a garbage planet surrounded by wormholes. A slave trader designated Scrapper 142 subdues him with an obedience disk and sells him as a gladiator to Sakaar's ruler, the Grandmaster, with whom Loki has already ingratiated himself. Thor recognizes 142 as a Valkyrie, one of a legendary force of female warriors who were killed fighting Hela eons ago. Thor is forced to compete in the Grandmaster's Contest of Champions, facing his friend Hulk. Summoning lightning, Thor gets the upper hand, but the Grandmaster sabotages the fight to ensure Hulk's victory. Still enslaved after the fight, Thor attempts to convince Hulk and 142 to help him save Asgard, but neither is willing.

Thor finds the Quinjet that brought Hulk to Sakaar. A recording of Natasha Romanoff causes Hulk to transform back into Bruce Banner for the first time since leaving Sokovia. 142 decides to help Thor save Asgard. Loki helps them steal one of the Grandmaster's ships. They liberate the other gladiators who, incited by two aliens named Korg and Miek, stage a revolution. Loki again attempts to betray his brother, but Thor anticipates this and incapacitates him. Thor, Banner, and 142 escape through a wormhole to Asgard, where Hela's forces attack Heimdall and the Asgardian citizens. Hulk defeats Fenris; Loki and the gladiators arrive to help, and a repentant Skurge sacrifices himself to save the citizens.