1. Morbius

Publisher - Marvel Comics
First Appearance - Amazing Spider-Man Vol. 1 #101 (1971)
Who he is - Morbius (also known as Nobel Prize winning biochemist, Michael Morbius) is technically not a supernatural vampire, but more of a scientific experiment gone wrong. Diagnosed with a rare blood cell deteriorating disease, Morbius secretly works on a cure and to his dismay is transformed into a super-powered being that must survive on plasma found in blood. If you ask me, the guy had it coming. Who told you to experiment using vampire bats!? C'mon, Morb!
What makes him so scary? - First of all, look at him. Secondly, he flies around in the darkest hour of the night looking to drain the plasma out of his next blood-filled victim with...creepy suckers on the palms of his hands. Oh, and he can hypnotize you too.
2. The Spectre
Publisher - DC ComicsFirst Appearance - More Fun Comics #15 (1940)
Who he is - Jim Corrogan is a murdered cop whose soul was refused access into the afterlife. He was granted supernatural powers by an entity known only as "The Voice" and given the responsibility to unleash vengeance on all evil.
What makes him so scary? - Well, for starters, The Spectre is practically a ghost. He lives forever and cannot be killed (since he's already dead). His power is seemingly unlimited, and very creative. For instance, he can transform the ground you are running on into a giant concrete, man-eating snake or turn the glasses on your face into razor sharp scissors. What makes him the scariest is that you never know when he's coming, he has absolutely no remorse and he always kills.
3. The Man-Bat
Publisher - DC ComicsFirst Appearance - Detective Comics #400 (1970) (Batman)
Who he is - In another experiment gone wrong, Dr. Kirk Langstrom hopes to repair his damaged hearing by acquiring the sonar abilities of a bat. While the experiment works, a slight side-effect is that he is transformed into a giant Man-Bat.
What makes him so scary? - What's scarier than werewolf? A flying Man-Bat of course! This thing can fly, has super-hearing and has super-strength, but the scariest thing is that it can put a hurtin' on the great Batman.
4. DeadMan
Publisher - DC ComicsFirst Appearance - Strange Adventures #205 (1967)
Who he is - Similar to Spectre, Boston Brand AKA Deadman is a supernatural ghost that was denied access to the afterlife. As an acrobat he was murdered by an assassin and now his spirit haunts the evil-doers.
What makes him so scary? - He's a creepy looking ghost. That should be reason enough, right? Wrong. He also has the ability to posses and take over any living being's body with the host having absolutely no recollection of the act. The good thing is that he does use his power for good.
5. The Black Lantern Corps.
Publisher - DC ComicsFirst Appearance - Green Lantern Vol. 4 #25
Who they are - This team is similar to the Green Lantern Corps, but oh so different. The black power rings grant power and life to the dead.
What makes him so scary? - They are basically a team of super-powered zombies whose only goal is to eliminate all life. The rings take over former super heroes like the Martian Manhunter and even Batman. On top of that here is their creepy Black Lantern oath that grants powers to their rings, "The Blackest Night falls from the skies. The darkness grows as all light dies. We crave your hearts and your demise. By my black hand, the dead shall rise"!
Tell me which spooky comic book character is your favorite! Let me know if you have any others.
Happy Halloween!