Kuk was the frog headed god who with the goddess Keket were the Ogdoad deities to represent darkness.
The ancient Egyptian deity that was considered evil and the patron of darkness is Apesh.
In the darkness the moon smiled in the sacred sky
In Greek mythology, Erebus was the personification of darkness, representing the shadowy realm that preceded the appearance of light. Erebus was believed to be the offspring of Chaos, the primeval void from which all creation emerged.
Erebus does not have a surviving artistic rendering from ancient Greece. He was only the personification of darkness.
I know there are other's, but the only one I can find for the time being is Kek. If you Google search Egyptian god of Darkness or even just Egyptian Gods, you're sure to find more.
Apophis is the Greek translation of the Egyptian name, Apep. Apep was the personification of Darkness and chaos, which would, by default, be opposed to light and order, which Ra represented. Please don't confuse the characters on Stargate with their actual mythological counterparts.
Set was the ancient Egyptian god of winds, storms, chaos, evil, darkness, strength, war, conflict, Upper Egypt.
The darkness fell like a heavy blanket over the town.
Translation: Dholma (ظلمة) Note that the proper Arabic word is Dholaam (ظلام).
Set was the god in charge of chaos, darkness, deserts and storms.
Seth, or Set, was the ancinet Egyptian god of winds, storms, chaos, evil, darkness, strength, war, conflict, Upper Egypt.
He was the god of the dead and would guide dead people through the darkness of the underworld.