Never heard of Dr. Destiny. Man Skeletor used to seem so original to me.
I would say Dr. Strange could make the list. The guy dresses like a bad Vincent Price character and is always trying to be all spooky and stuff. Something that the venture bro's picked up on when they spoofed him. Also as you mentioned, man-bat. Of course Morbius would fit the bill as well. Blade not so much unless you count "Blackula" as a halloween classic. Also if you are going to count Swamp Thing then you really have to mention the Man Thing. Man Thing first appeared in May of 71 and Swamp Thing didn't appear until July. Although now Man Thing is some sort of magical zombie puppet thingy they started out as very similar books. Though I do certainly understand why swamp thing is more popular.
Might as well throw in the ENTIRE batman cast as well. Think about it, grown men and women dressing up as either animals (batman, robin, catwoman, ect) characters based on pop-culture spoofs (The Mad Hatter, Scarface) or classic halloween costume ideas (Joker, Harley Quinn). Everyday is Halloween in Gotham. 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. I mean yeah other comics have a bunch of costumed freaks as well, but their costume is generally a super hero one... you know tights with their initials on them. Gotham City villians (and heroes for that matter) look they they robbed the local spencers and suited up.