Seriously, you'll be hard pressed to think of a batman villian that wouldn't be considered either a monster straight from a horror movie and/or a guy in a halloween costume if they were taken out of the context of the books.
Julian Day comes to mind...Poison Ivy somewhat.
Next year, I want to see Demogoblin and Nightwatch though.
Next year, I want to see Demogoblin and Nightwatch though.
Well Posion Ivy always reminded me of the classic "EVE" costume but that could be argued. As for Calendar man he literally used to dress up as a giant calendar, so again, guy in a lame off-the-shelf halloween costume.