Sven is the loyal pet reindeer and companion of Kristoff, a rugged mountain man.
Sven is goofy, loyal and rather childish. He spends most of the film by Kristoff's side, acting as his closest friend (even in their younger years) and conscience. And while Sven may not seem incredibly intelligent, he does have a strong moral character. Throughout the film, he constantly convinces Kristoff to do the right thing, including assisting Anna in her journey to find Elsa, and later returning to Arendelle to confess his love for the princess after their adventure comes to a conclusion. Along with Kristoff, Sven also seems to be greatly close to Olaf, enjoying the snowman's antics and eventually creating a close bond throughout the course of the film. As a running gag, however, Sven tries to grab a bite of Olaf's carrot nose. In the end of the film, he manages to do just that, but immediately returns it, showing he was merely being playful with his new-found friend, much to Olaf's delight.
The key to his character, Sven lacks qualities of an actual reindeer, aside from appearance and vocal affects. Instead, he's shown to have the personality of a dog, as he's constantly seen panting (though reindeer tend to do this, as well), wagging his tail, and performing the "play bow" stance, which dogs tend to use as a way to initiate playtime.
- Sven's original name was Thor.