(Here was my first post- The 10 best DC horror stories I could think of…)
Sandman #6: 24 Hour Diner
There are several issues you could choose from Sandman, but this one stands out. Dr. Destiny, DC’s own Freddy Krueger, walks into a diner and causes complete and utter horror for everyone inside who was unfortunate enough to cross his path.
Batman 663: the Clown at Midnight
You could do a whole list of just Joker stories, but if I had to pick just one, I’d go with the Clown at Midnight- Grant Morrison’s prose story about the Joker’s ‘rebirth’ after being shot in the face by a Batman imposter.
The Flash: Iron Heights
This story delves deeper into the Flash’s version of Arkham, Iron Heights, and introduces the world to Murmur. Murmur is a serial killer who targets victims who speak too loudly or too much (talk show hosts, radio DJ’s, etc). He cuts out their tongues or uses his ‘Frenzy Virus’ on them, which melts your esophagus.
Superman the Animated Series: Fun and Games
Episode 4 from season 1 of Superman the Animated Series. I know its a kids show. But the Toyman here is sooooo creepy. Like Jigsaw before that was a thing. This will always be one of my favorite examples of taking a goofy character and showing them in a new light.
Catwoman #12-16: Relentless
If you’ve seen the new Birds of Prey film, this version of Black Mask is what they were going for. This was the first time I can remember that he was shown to be a sadistic torturer. It set the bar high, and really highlighted how terrifying he can be.
Solomon Grundy by Scott Kolins
This mini series by Scott Kolins takes Grundy on a tour of DC’s horror characters (the Demon, Bizarro, Frankenstein) while highlighting why Grundy himself is one if their greatest. The children’s rhyme that inspired his name. That fact that no matter how he’s killed, he’ll rise from the dead.
Secret Six #1-6: Unhinged
Gail Simone writes some terrific horror stories, and this one is one of my favorites. The Secret Six are given a ‘Get Out of Hell free’ card made by Neron and this story is about the chaos that causes. Junior is the main villain of the story and is delightfully twisted.
Swamp Thing #21: the Anatomy Lesson
Alan Moore’s second issue of Swamp Thing changed how he was seen forever. Swamp Thing always believed himself to be a human who became a monster, but this issue asks what if that wasn’t the case at all, and that everything we believed was a lie?
Batman #542-543: Faceless
Batman hunts a serial killer named Faceless who dresses as grotesque versions of his victims before he kills them. Kelley Jones and horror go hand in hand, and this was one of my favorites of his.
Green Lantern #43
Someone mentioned Blackest Night already- I think this issue in particular really showcases how demented the Black Hand is. Geoff Johns is one of those writers who can take most any villain and show you the darkest version of them.
Here’s to many more 
