He hung motionless in a black, forbidding sky and at first thought he was suspended somewhere in the intrasolar deeps much closer to the Sun than on Earth. But then he realized that the dully gleaming orb which floated before his dreaming vision was not the Sun. Ugly dark blotches mottled the dull orange surface and great columns of spinning flame arced around the rim.... [He watched] the titan sunspots drift slowly across the hideous disc, at times growing larger and merging into great gaping chasms in the fiery atmosphere, while at others dwindling almost to nothingness.... Something was stirring deep within that fiery atmosphere; something monstrous that roared an insatiable anger against the chains of the Elder God which had bound it there for an eternity.... Unable to resist, utterly powerless to control his movements, he was diving headlong towards that ravening chaos, that age-old intelligence which was Cthugha.
—John Glasby, "The Dark Mirror"
Cthugha resembles a giant ball of fire. He is served by the Flame Creatures of Cthugha. Fthaggua, regent of the fire vampires, may be his progeny. He has at least one other known progeny, the being known as Aphoom-Zhah.
Several cults to Cthugha can be found the east including The Nestarian offshoot of Zoarostrianism centered in Bombay (a large number of the members of which are unaware that the entity they worship is Cthugha)and a smaller independent cult known as the Slaves of the Flame Undying based in Egypt.
A large amount of information on Cthugha and his worship can be found in the collection of scrolls known as The Letters of Nestar.