In Norse mythology, Sleipnir (Old Norse: "slippy" or "the slipper") is the eight-legged horse who serves as Odin's trusted steed. He is the son of Svaðilfari and the god/jötunn Loki, the latter of whom is actually his mother, having given birth to Sleipnir in the form of a mare. Sleipnir is described as the best and fastest of all horses.
Sleipnir
Theories
John Lindow theorizes that Sleipnir's connection to the world of the dead is a kenning in which Sleipnir appears as a concept according to the skald Úlfr Uggason, who speaks of the "sea Sleipnir" in his Húsdrápa describing Balder's funeral. Lindow argues that Sleipnir's eight legs can be seen as an indicator of great speed.
Reception
Sleipnir is, according to legend, also the reason why the Ásbyrgi Gorge in Iceland is shaped like a horseshoe. When Odin rode him across the deserts of the Arctic, the horse is said to have slipped and set foot on northern Iceland. This is why the gorge is sometimes referred to as Odin's footprint.
Modern esoteric reception
Hilda Ellis Davidson writes that Odin's eight-legged horse is the typical steed of a shaman and that on a shaman's journeys to heaven or the underworld, he is always depicted riding a bird or animal. Davidson further states that while the creature may vary, the horse is usually common in regions where horses are found, and furthermore, Sleipnir's ability to carry the god is a typical characteristic of the shaman's horse.
Davidson refers to the controversial religious phenomenologist Mircea Eliade, who writes that the eight-legged horse is the shaman's horse par excellence. It is found, for example, in Siberia and among the Muria, where it is always related to ecstatic experience. On Sleipnir Odin can ride through all worlds. It is believed by some historians that the eight legs are a symbol for the legs of four people carrying a coffin. Thus, the steed also allows a rider to be carried to the underworld. Odin rides Sleipnir to Niflheim to find out about Balder's dreams.