The Great Stallion is the primary religious figure in centaur culture. The Great Stallion does not feature in the Engelite Pantheon, (it is the belief of the centaurs that the Great Stallion predates the arrival of Tyrrus on Earth,) and attempts to include the Great Stallion within the Engelite Pantheon through the writing of new religious tomes has often been met with sheer repulsion in centaur circles.
The Great Stallion is said to be constantly charging through the night's sky. The stars are supposedly members of his divine herd, the souls of the stallions of old, and through their placement in the sky the Great Stallion sends prophecies to the centaurs of future events. It is unknown to humans what other role the Great Stallion is supposed to provide other than this- perhaps it is none. There are some centaurs that believe the Great Stallion to be a horse, and for Tyrrus to be a man, gods of sky and earth, and the centaurs exist in neutrality to scry the divine wills of both, who are foreign and alien to one another. It seems this idea of the Great Stallion being a literal horse, rather than a centaur, is quite pervasive in centaur culture, (though the idea of Tyrrus being a parallel to the Great Stallion is frowned upon by most.)
It is said that the unitaur is spiritually a child of the Great Stallion, though not literally. The Great Stallion is not worshipped by the satyrs, despite their proximity to the centaurs in the Great Plains. There are many human scholars that equate the Great Stallion of the centaurs and the Old Goat and the Maiden Ram of the satyrs as being part of the same overall pantheon- perhaps erroneously. It is unknown whether or not the onocentaurs also believed in the Great Stallion, though divine intervention might explain the great feats they accomplished.
As the Great Stallion is not a part of the Engelite Pantheon, it is widely regarded by those outside of centaur culture to be a fabrication.