Sven is a non-speaking reindeer, who has been a companion to Kristoff since both were young. Kristoff understands what Sven communicates through his facial expressions and movements, and he sometimes voices Sven's thoughts. The two of them work together harvesting ice at the beginning of the film, with Sven pulling the sled that carries the ice. Following this, they meet several trolls that are disguised as rocks, and a female troll adopts Sven and Kristoff. Years later, the two of them travel together to the kingdom of Arendelle on the coronation day of princess Elsa. In the forest near Arendelle, they subsequently meet princess Anna, Elsa's estranged sister, who asks them to take her to the North Mountain — Elsa's location after fleeing from the kingdom because of unwillingly placing it under an everlasting winter. On their way, Sven and Kristoff lose their sled after being chased by wolves, but Sven convinces Kristoff to continue helping Anna nonetheless. Later, they meet a talking snowman created by Elsa, Olaf, who offers to guide them. Sven alongside the others manages to help Anna reach Elsa's newly-created ice castle, but after Elsa casts ice magic on her, the group brings Anna back to Arendelle. Soon after they leave Anna in her maids' care, Sven shows his intention to return along with Kristoff to her, and they immediately start heading toward Arendelle once they realize Anna is in danger on account of a snowstorm that is forming. On the frozen fjord near Arendelle, Sven then saves Kristoff from falling into the icy water. Because of their actions throughout the story, Sven and the others help overcome Hans, the evil acting leader of Arendelle, and contribute to Anna's permanent reunion with Elsa and to Elsa being able to bring summer back in the end. As a result, Elsa awards a medal to Sven, and Anna offers him and Kristoff a new sled.
Meanwhile, through her magic, Elsa manages to escape her cell by freezing her shackles until they become so brittle that they break, then freezing the wall of her cell until it collapses. Hans chases after her into the frozen fjords as a harsh blizzard consumes the kingdom. He eventually stumbles upon her, and claims to her she cannot escape all the horrible things she has already done. Elsa pleads for mercy, and asks him to take care of her sister for her, to which Hans responds by telling her that Anna has died from Elsa freezing her heart (or so Hans thinks, since Olaf has found Anna and helped her escape). Elsa collapses, and whilst she is distracted, Hans pulls out his sword and prepares to stab her. As he is swinging, Anna suddenly arrives and jumps in front of Hans' sword path, completely freezing solid just before Hans' blade strikes her and shatters. Anna's freezing causes a forceful blast, knocking Hans off his feet and rendering him unconscious.
His first appearance in Frozen is during Anna and Elsa's childhood as an inanimate snowman. Later, Olaf is recreated offhandedly during the first chorus of "Let It Go", and unknown to Elsa, comes to life. Two days later, Anna and Kristoff cross paths with Olaf while traveling through a meadow. Anna's first instinct is to give Olaf the carrot nose that he had been missing. Before they continue on their way, Olaf sings a short number fantasizing about what it might be like to experience summer heat, blissfully unaware that he'll melt. Olaf then guides Anna and Kristoff to Elsa's ice palace.
At a trading post on her journey, Anna meets a mountain man named Kristoff, an ice harvester who agrees to lead her to the North Mountain, where he knows that a magical phenomenon has occurred and helps her escape a pack of wolves, resulting in his sled being destroyed after falling down into a large hole and catching fire. The duo and Kristoff's reindeer Sven, are chased by wolves on the way and encounter Elsa's snowman, Olaf, who was unknowingly brought to life by Elsa and later leads them to her palace. The sisters reunite, but Elsa is reluctant to help Anna by ending the eternal winter. Upset, she loses control of her powers, striking Anna in her heart. Desperate to get her sister to leave, Elsa creates a giant snow creature, and it throws Anna and her friends away from the palace. Upon noticing Anna's hair is turning white, Kristoff takes her back to his adoptive family of trolls. Pabbie tells Anna that her heart has been frozen by her sister's magic and only an act of true love can save her from freezing completely. Kristoff, believing that a romantic kiss from Hans will heal her, takes Anna back to the kingdom.
When he awakens several moments later, he finds Arendelle thawed and peace restored. Enraged by what Hans did to Anna and what he was doing to Elsa, Kristoff approaches Hans intending to attack him, but Anna intervenes. Instead, Anna confronts Hans, and the sight of her alive and well confuses Hans, prompting him to ask how she survived the frozen heart curse. She tells him that the only person who has a frozen heart is Hans himself for what he did to her and Elsa. Anna turns her back to him, much to Hans' disbelief, then, in a swift movement, turns around again and punches him in the face and off the side of a ship. Humiliated and defeated, Hans is last seen imprisoned on a ship heading back to the Southern Isles. According to the French dignitary, Hans is set to receive an ultimate (and unspecified) punishment from his older brothers.
Kristoff is the first major character to appear in the movie, and is introduced in "Frozen Heart", as an eight-year-old orphan boy with his baby reindeer, Sven, who becomes his best friend. He attempts to mimic the elder ice harvesters, with mixed success. Later that night, Sven is pulling him through the woods when the two horses belonging to the royal family of Arendelle ride past him at speed while transporting Anna to the trolls. Kristoff becomes intrigued as one of them is leaving behind a trail of ice (as that horse is carrying a distraught Elsa). From a distance, Kristoff watches as Pabbie, leader of the trolls, heals Anna's head. At the same time, one of the female trolls Bulda adopts Kristoff as her own child.
As Elsa grieves for her sister, Anna begins to thaw, since her choice to sacrifice herself to save her elder sister rather than herself constitutes "an act of true love". Realizing love is the key to controlling her powers, Elsa is able to thaw the kingdom and use her magic safely in public. Anna confronts Hans, who thought Elsa froze her heart. But Anna reminds him that he is the one with the frozen heart and punches him in the face, making him fall off the ship into the water. She then buys Kristoff a previously-promised new sled and they share a kiss, starting their new relationship. Anna and Elsa's sisterly bond is rekindled, with Elsa promising never to shut the castle gates again, much to Anna's joy.
On November 28, 2014, in an interview with The Daily Telegraph, when asked about the possibilities of a Frozen sequel and a stage show, Idina Menzel mentioned "they’re all in the works." She also talked about her involvement in these projects: "Ah, yeah sure... Not the stage show – I don’t know what will happen with that – but the movie hopefully. We’ll see. I’m just going along for the ride." However, on December 1, when the subject came up again during an interview on the Today show on the NBC network, Menzel said, "You know, I have no idea. I just assumed that because it’s so successful that’s what they’re up to!"
On August 5, 2014, Variety reported that Lee had selected her next project: a screenplay adaptation of Madeleine L'Engle's 1962 novel A Wrinkle in Time, for which Disney already holds the film adaptation rights. However, Lee will continue to participate in Disney Animation's development process (i.e. giving notes on other projects, the same process by which she became involved with Frozen in the first place).
In a March 2015 interview with BuzzFeed about Frozen Fever, the directors addressed and refuted the recurring rumors about a possible feature-length sequel. Buck joked about how whenever they saw such rumors, he and Lee would ask each other, "Are we?" Around the same time, Lasseter reiterated to Variety his philosophy as to sequels (while discussing Toy Story 4): "We do not do any sequel because we want to print money[.] We do it because each of these films was created by a group of filmmakers, and to my mind, they are the owners of that intellectual property. So we look at it with the simple question: Is there another story we can tell in this world? And that desire has to come from the filmmaker group. Sometimes, the answer is an obvious yes. And sometimes it’s, ‘I love the characters and I love the world, but I don’t have an idea yet.’ And sometimes it’s just, ‘that movie is a great movie,’ and the filmmaker wants to move on and do something else. And that’s fine, too."
Olaf appears in the short film Frozen Fever where he is caught stuffing a piece of cake into his mouth by Elsa. When Elsa is not paying any attention, Olaf quickly spits out the cake, only to put it back on the cake. Then, he is found helping Kristoff and Sven trying to get rid of the snowgies that are being produced every time Elsa sneezes. At the end of the special, he is seen helping Kristoff and Sven escort the snowgies to live with Marshmallow at the ice palace on the North Mountain.
Olaf is featured in the sequel to Frozen, Frozen II; released on November 22, 2019 in the US.
On June 11, 2015, Hong Kong Disneyland launched a "Frozen Fun" event that runs through August 30. The major feature of the event is the "Frozen" Festival Show presented at the Crown Jewel Theatre inside Frozen Village, an area located in the “Black Box” space known as "The Pavilion", between Adventureland and Grizzly Gulch. Also inside Frozen Village is Frozen Festival Square where the meet-and-greet with Olaf, a toboggan ride, and Oaken’s Trading Post are located. Other attractions are "Frozen Processional", meet-and-greet with Anna and Elsa in Fantasyland as well as lessons on how to draw Olaf at the Animation Academy.
On December 5, 2014, the Disneyland Resort announced a "Frozen Fun" event at Disney California Adventure. While some of the attractions were made available starting on December 20, "Frozen Fun" officially began on January 7, 2015. The event included For the First Time in Forever: A Frozen Sing-Along Celebration at the Muppet*Vision 3D theater, "Olaf’s Snow Fest" (featuring a meet and greet with Olaf), Wandering Oaken’s Trading Post, "Freeze the Night! A Family Dance Party" (temporarily replacing Mad T Party), and "Anna and Elsa’s Royal Welcome", a meet-and-greet at the Disney Animation Building (replacing the meet-and-greet in Disneyland Park) as well as lessons on how to draw either Olaf or Marshmallow at the Animation Academy. In addition, Disneyland received a Frozen play at the Fantasy Faire, and an update to the Storybook Land Canal Boats to include the village of Arendelle from the film.
When asked about future sequels, Del Vecho explained in March that Buck, Lee and he "work very, very well together, so I believe we will be developing a new project. But I don't know what that is right now." In late April, Walt Disney Studios chairman Alan F. Horn said that "we haven't really talked about a sequel" because the studio's current priority is the planned Broadway musical, which will require "four or five" additional songs to be written by Lopez and Anderson-Lopez. When asked in May about a sequel during an interview with CNBC's David Faber, Disney chairman and CEO Bob Iger said that Disney would not "mandate a sequel" or "force storytelling", because to do so would risk creating something not as good as the first film. In the same interview, Iger also expressed the hope that the Frozen franchise "is something that is kind of forever for the company" similar to The Lion King." In June, Lee confirmed that chief creative officer John Lasseter had expressly granted her and Buck the freedom to explore whatever they were "passionate about": "We don't know what it is yet ... We’re actually going to start from scratch. It’ll be something completely brand new."
In the short film Frozen Fever, Kristoff helps Elsa plan a surprise birthday party for Anna. While taking Anna on a birthday treasure hunt throughout the kingdom, Elsa comes down with a cold and unknowingly creates little snowmen called "snowgies" with each sneeze, which create trouble for Kristoff, Sven, and Olaf. Kristoff and Olaf later take the snowgies up to Elsa's ice palace to live with Marshmallow.
On July 5, 2014, Disney's Hollywood Studios at Walt Disney World launched a "Frozen Summer Fun" program which was to run through September 1, and which included a daily parade, sing-along show, dance party, and fireworks show; an indoor ice skating rink and a merchandise shop; and Frozen décor throughout the theme park. In response to strong demand, Disney Parks subsequently announced on August 7 that Frozen Summer Fun would be extended to September 28.
In the short film Frozen Fever (2015), Sven contributes to the arrangements for Anna's birthday party, but he falls asleep along with Kristoff and Olaf in the meantime. They wake up because of several small living snowmen, who have been created by Elsa's sneezes and who wish to reach Anna's birthday cake. Trying to stop them, Kristoff accidentally spills a drink over Sven and himself. While running after the snowmen in an attempt to catch them, Sven ends up with his tongue stuck to an icy poll. Later, Kristoff climbs on top of Sven and holds the birthday cake in order to present it in this manner to Anna. After Anna and Elsa arrive at the kingdom's gates, Sven slices the birthday cake with the help of his antlers. Eventually, Sven brings the snowmen to Elsa's ice castle alongside Kristoff and Olaf.
Hans does not physically appear in Frozen II but his mentioned many times throughout the movie and he appears in the snowy manifestations of Elsa's past which Elsa destroys his figure due to her being bitter at him for his past actions.
Hans briefly makes an appearance in Frozen Fever where he is seen cleaning up horse manure in the Southern Isles as part of his punishment from his family in his actions against Queen Elsa and Arendelle. After Elsa sneezes into a large sounding horn, she creates a large snowball that flies over to the Southern Isles and accidentally catapults Hans into a pile of manure, causing all the horses in the stable to laugh at his misfortune.