The Odinsteed, The Sleipnir-Kin
The origin of these bizarre horses is unknown. Though they bear resemblance to Odin's 8-legged horse, Sleipnir, there is much debate around the myth that they are actually descended from such a creature.
The only reported cases of someone riding an Odinsteed are from so long ago that they are always considered legends and children's tales. Even in these tales, however, the riders are great heroes who have performed a service for the horse in the past.
The Odinsteeds are said to be majestic and powerful, but as such, proud and hard to train. The claims average anywhere from 18 to 30 Hands in height and it is said they can easily outrun anything with less legs.
A Twisted Truth, Perhaps?
The Odinsteed are not great horses of the blood of Sleipnir. They are indeed rare and special, though not in a pleasant way. They are a breed of black-maned horses infused with the blood of Giant Spiders. With the ability to weave and crawl among large webs high above the ground, it is rare to catch an Odinsteed unawares.
Odin may have ridden a majestic eight-legged steed in Norse mythology, but the namesake Odinsteed are a vile and twisted horse-spider hybrid. With eight powerful and multi-jointed legs, eight beady little eyes sprinkled about an equine facade, internal mechanisms for creating webbing that leaves their hind quarters looking bulbous and bloated, and a set of horrible hidden mandibles that it can produce from a seemingly horse-like mouth, these horses are hardly the legendary creatures of good that Sleipnir was.
Their origin is uncertain, thought almost definitely a result of horse and spider magical cross-breeding. They now reside in the deep, dark, places of the earth much like other Giant Spiders and horrific monsters.