Sleipnir is an eight-legged horse that serves as the All-father Odin's noble steed.
Sleipnir has eight legs and is unnaturally fast, which makes him the quickest horse of all Nine Realms. He is completely loyal to Odin, his master. In addition, Sleipnir served as Odin's companion during the era of Asgardian's expansion of the Nine Realms.
Sleipnir is Odin's destrier, his faithful steed, which accompanies him in his battles.
When Hela usurped the Asgardian throne after invading the palace, she revealed a hidden mural from the present one, which detailed pictures of Odin atop Sleipnir, and Hela herself atop Fenris. The mural showed the two accompanied by the Berserkers as they conquered the Nine Realms.