Well here is something I've never seen before, thanks to my buddy Matt for sharing. This is a Ben Cooper Cousin Eerie Halloween costume based of course on the mascot for the Warren magazine Eerie.that ran for nearly 20 years.
And it's a great costume too! Nice mask and smock action here.
According to Matt, there is a costume for "Uncle Creepy" as well but it must be rare as he doesn't own one.