- Good ol' Alan Moore created the prison planet Ysmault, and populated it with Eldritch Abominations who prophecized the end times of the Corps.
- Half the crap drawn by Ethan Van Sciver. Especially his version of Parallax-possessed heroes.
- The entire Sinestro Corps, in a literal sense.
- Parallax. Being an Emotion Eater, it's a primary weapon. Plus his appearance looks pretty demonic.
- Kryb. Her method of instilling fear? She kills parents and steals their infant children for herself.
- Even worse, she genuinely loves the children in question. Truly and sincerely, with all her heart. To the point that a Star Sapphire can use her love as a tether to track the children in question. High Octane Nightmare Fuel should simply not be crossed with woobiedom!
- Romat-Ru. He killed thousands of children.
- The Third Army - Hideous, emotionless monsters designed by the Guardians to replace the Green Lantern Corps and thus are able to withstand everything a Green Lantern Ring can throw at them and effortlessly break through any barriers they throw up. Oh, and rather than kill you, they instead forcibly turn you into one of them, and you'll be aware of what's happening when they do so.
- Black Hand returns (again) for his Villains Month issue and once more causes a (so far local and non-Black Lantern) Zombie Apocalypse. This is Nightmare Fuel enough, but when he runs into policemen who keep mowing down his zombies, he reanimates dead viruses inside one of the cops, quickly killing and reanimating him from the inside. Yikes. As if that's not enough, at the end he rips off his own hand and replaces it with that of (zombie) Martin Jordan, just so he can kill Hal with his father's hand when they next meet.
Nightmare Fuel / Green Lantern