Der Schwarze Pharao war ein sog. Gegenpharao.
Im Cthulhu Kanon wird er als der Pharao beschrieben, der aus der Geschichte getilgt wurde - was wohl nicht so ganz geklappt hat.
CTHULHU MYTHOS ENCYCLOPEDIA, Seite 194 f.
NEPHREN-KA (also known as the Black Pharaoh). Mythical ruler of ancient Egypt. The earliest such figure, mentioned in the Necronomicon, was a lord of Acheron buried in a shroud containing the secrets of Nyarlathotep. Little more is known about him, however.
Most scholars are in firmer agreement that Nephren-Ka was the last pharaoh of the Third Dynasty. Legend has it that Nephren-Ka was a mighty sorcerer, the greatest of Egypt's priest-kings. He made a deal with Nyarlathotep in the lost city of Irem, and upon his return revived the worship of that god in that land (indeed, some even considered him to be Nyarlathotep's avatar) and ruled the land as pharaoh. During his reign the priesthoods of Bast, Anubis, and Sebek flourished. The Black Pharaoh is also credited with the discovery of the Shining Trapezohedron.
There was great discontent within the populace due to these changes, and soon thereafter the people of Egypt were in revolt.
In the end, Sneferu, the founder of the Fourth Dynasty who had received aid from the goddess Isis, prevailed over the Dark Pharaoh. Nephren-Ka made his way toward the coast, in order to escape to a "western island." Enemy forces cut him off, however, somewhere near the site of modern-day Cairo. The evil pharaoh and his priests vanished, having buried themselves in an underground vault whose location has remained a secret to this day. Baffled, Sneferu declared the Black Pharaoh dead and had Nephren-Ka's name stricken from all records and monuments.