What color are demons?

Answer

Over the years the way that demons have been depicted has varied dramatically. Sometimes they are little more than sinister-looking people, or they could be gross imps and gargoyles, even glorious looking, almost angelic creatures (since they were supposed to be fallen angels anyway).

So, there is no one color that demons are supposed to be.

You will commonly see them depicted in earth tones (dark browns, reds, greens, etc) representing their fallen status, sometimes more vibrant reds representing Hell, but also a wide variety of vibrant colors representing the various passions or sins they represent. Ceremonial magicians have attributed specific colors to specific demons (and angels) over the years, but their attributions are far from consistent.