K'Thoutek

K'Thoutek was a large comet (300 miles diameter) in Realmspace that circumnavigated the sun in an extremely elliptical orbit. Its only remaining inhabitant of a once large group of oortlings was their greatest wizard, turned into an undead haunt bent on revenge against the illithids who destroyed the colony. The appearance of the comet K'Thoutek was seen as a sign for the birth of a powerful person by astronomers on Toril.