Thread:NoFourthWall/@comment-9289481-20131110223403/@comment-1988716-20131111035846

Actually, A was a very prominent character in The Slender Man Mythos, if I recall correctly. He appeared in a lot of stories, to the point where he pretty much was open-source, and he served the exact same purpose as UXPs do here.

That is probably why he was labelled one.