Shadowfax is the horse ridden by Gandalf in J.R.R. Tolkien’s The Lord of the Rings.
Shadowfax belongs to the horse-lords of Rohan and is described as the greatest of the Mearas, a legendary race of exceptionally intelligent and swift horses. King Théoden eventually allows Gandalf to take him, after the wizard’s imprisonment on Orthanc and escape with the help of Gwaihir.
The horse’s name means “shadow-fax,” referring to his coloring: a silver-grey coat and a mane that appears white. Shadowfax can run extraordinarily fast and understands human speech, although Tolkien presents him as a powerful animal rather than a talking character.
Brego is associated with Aragorn in adaptations of The Lord of the Rings, while Hasufel is another horse used by members of the Fellowship. Bill Ferny is a Hobbiton-area character, not a horse.