They are grey-colored demons with short black horns and a blood-stained mouth filled with long, crooked teeth.
They behave very similar to Frowning Gapers, but move faster and phase in and out of visibility.
- They bear strong resemblance to demons who were summoned by one of Satan's unused attack methods from the Artbook.
- From the game's files, one of the sprites from the Null's sprite sheet has bloody tears, though it could be just the Frowning Gaper's head being recolored.
- Nulls are one of the Gaper types not to spawn into headless variants upon death. Three others being Cyclopia, Blue Gaper, and Greed Gaper.