Sleipnir is Odin's eight-legged horse in Norse mythology. Sleipnir was described as being the best horse among the Aesir and men. He can ride through the sky, over water, and between the nine realms. His name means "the slipper," aluding to his speed. He was born from a union of Loki in the form of a mare and the horse Svadilfari.
Long ago, after the war between the Aesir and Vanir, the gods promised a giant that if he could rebuild the walls of Asgard within an agreed-upon time, he would receive the goddess Freya as his wife, the sun and the moon. The giant used the magical stallion Svadilfari to progress with his task much swifter than predicted. In order to delay the giant in completing the wall on time, Loki changed himself into a mare and seduced Svadilfari. After successfully preventing the giant from completing the wall by luring Svadilfari into the woods, Loki gave birth to the gray, eight-legged foal some time later.
"The steed of Odin in Norse mythology. He has eight legs and can fly through the sky as well as travel underwater. He was also not infrequently depicted as a centaur. His name means "gliding smoothly." Long ago, the gods promised the giants that if the giants could rebuild the walls of the god's fortress of Asgard within an agreed-upon time, the giants would receive the goddess Freya. The giants used the magical horse Svadilfari to complete their task on time. Loki changed himself into a mare and seduced Svadilfari. Thus was Sleipnir born."
—Shin Megami Tensei IMAGINE Compendium
Sleipnir can be encountered within Shibuya's Celu Tower instances, appearing alongside Odin in silver's boss room. There are two mountable variations within game — one normal and one with increased resistances and a feature boosting its natural speed.
Shin Megami Tensei IV Apocalypse[]
"Odin's eight-legged horse of Norse lore. Its father was Svadilfari and its mother was Loki, in the guise of a female horse. It is also used as a symbol of the gallows."
"Odin's eight-legged horse. Its father was Svadilfari and its mother was Loki in the guise of a female horse. It is also used as a symbol of the gallows."
—Devil Summoner: Soul Hackers 3DS Compendium
DemiKids Light & Dark[]
"A super-fast, eight-legged horse in blue armor that runs at incredible speeds."
Known as Slepnir, he can perform the combo Blizzard with Fenrir. Slepnir also has the power Hyper Speed.
Devil Survivor 2[]
"Odin's eight-legged horse of Norse lore. Its father was Svadilfari and its mother was Loki in the guise of a female horse. It is also used as a symbol of the gallows."
—Devil Survivor 2 compendium
Shin Megami Tensei: Liberation Dx2[]
"Odin's eight-legged horse of Norse lore. Not only can it run at incredible speeds but it can also fly and ferry the dead to the heavens. Its father was Svadilfari and its mother was Loki in the guise of a female horse, given to Odin as a gift. It is also used as a symbol of the gallows. The tree from which Odin himself hug in the underworld to retrieve the Runes, was also called Sleipnir."