Could the asgardian god of fear in "Fear Itself" have anything to do with the Dark Man
Probably not due to his obscurity but I always liked the character.
I was going to mention him, as well. However, I think the Dark Man was more of an conceptual entity than a god representing a fear. The page where the Dark Man reveals his true nature always led me to believe that he was an abstract being.
It's interesting that maps of the Nine Worlds have incorporated the Dark Man's domain, despite him appearing in only one issue.