Aldebaran (The Eye of the Bull) is the star of the Great Old One Hastur. It lies in the constellation of Taurus, near the Pleiades. Hastur inhabits the Lake of Hali on a planet circling a dark star near Aldebaran. The Celaeno Library might also be located here.
Aldeberan as it appears in the mythos may be connected with Marion Zimmer Bradley's Darkover novels, which also use the Hastur myth.