Unknown Chaos Cults

The Unknown Chaos Cults is a tag for artwork that I couldn’t determine the faction of the Chaos Cult in the image. This is because either the artist didn’t say, or I couldn’t find any markings to lead me to what it might be. This is not for the Homebrew 40K as there is a separate 40K tag for that. If you do know of the faction in the image, please let me know.