Thor: Ragnarok is a 2017 American superhero film based on the Marvel Comics character Thor, produced by Marvel Studios and distributed by Walt Disney Studios Motion Pictures. It is the sequel to Thor (2011) and Thor: The Dark World (2013), and the 17th film in the Marvel Cinematic Universe (MCU). The film is directed by Taika Waititi from a screenplay by Eric Pearson and the writing team of Craig Kyle and Christopher Yost, and stars Chris Hemsworth as Thor alongside Tom Hiddleston, Cate Blanchett, Idris Elba, Jeff Goldblum, Tessa Thompson, Karl Urban, Mark Ruffalo, and Anthony Hopkins. In Thor: Ragnarok, Thor must escape the alien planet Sakaar in time to save Asgard from Hela and the impending Ragnarök.
Two years after the battle of Sokovia, 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 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. After exposing Loki, Thor forces him to help find their father, and with directions from Stephen Strange at the Sanctum Sanctorum in New York City, they locate Odin in Norway. Odin explains that he is dying, Ragnarök is imminent despite Thor's efforts to prevent it, and his passing will free his firstborn child, Hela, from a prison she was sealed in long ago. Hela was the leader of Asgard's armies, conquering the Nine Realms with Odin, but Odin imprisoned her and wrote her out of history after fearing that she had become too ambitious and powerful. Odin dies as Thor and Loki look on, and Hela appears, destroying Thor's hammer Mjolnir. She pursues the two as they attempt to flee through the Bifröst Bridge, forcing them out into space. Arriving in Asgard, she defeats its army and kills the Warriors Three. She then resurrects the ancient dead who once fought with her, including her giant wolf Fenris, and appoints the Asgardian Skurge as her executioner. Hela plans to use the Bifröst to expand Asgard's empire, but Heimdall sneaks in, takes the sword that controls the Bridge and begins hiding other Asgardians.
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 old 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. He soon manages to escape the palace and finds the Quinjet that brought Hulk to Sakaar. Hulk follows Thor to the Quinjet, where a recording of Natasha Romanoff causes him to transform back into Bruce Banner for the first time since Sokovia.
The Grandmaster orders 142 and Loki to find Thor and Hulk, but the pair come to blows and Loki forces her to relive the deaths of her Valkyrie companions at the hands of Hela. Deciding to help Thor, she takes Loki captive. Unwilling to be left behind, Loki provides the group with the means to steal one of the Grandmaster's ships. They then 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 leaves him behind, where Korg, Miek, and the gladiators soon find him. Thor, Banner, and 142 escape through a wormhole to Asgard, where Hela's forces are attacking Heimdall and the remaining Asgardians in pursuit of the sword that controls the Bifröst. Banner transforms into Hulk again, defeating Fenris, while Thor and 142 fight Hela and her warriors. Loki and the gladiators arrive to rescue the citizens, and a repentant Skurge sacrifices himself to enable their escape. Thor, facing Hela, loses his right eye and then has a vision of Odin that helps him realize only Ragnarök can stop her. He sends Loki to retrieve Surtur's crown and place it in the Eternal Flame. Surtur is reborn and destroys Asgard, killing Hela and himself, as the refugees flee.
Aboard the Grandmaster's spaceship, Thor, now king, reconciles with Loki and decides to take his people to Earth. In a mid-credits scene, they are intercepted by a large spacecraft.[N 2] In a post-credits scene, the overthrown Grandmaster is confronted by his former subjects.