|Powers and Abilities
| Demon-Killing Knife
| 2.09 Croatoan
2.21 All Hell Breaks Loose: Part One
3.01 The Magnificent Seven
4.07 It's the Great Pumpkin, Sam Winchester
5.04 The End
5.20 The Devil You Know
5.21 Two Minutes to Midnight
Most black-eyed demons are interchangeable, but there are some demons who differentiate themselves.
– Nicholas Knight, The Essential Supernatural: On the Road with Sam and Dean Winchester
Types of Mutations
While it does not turn humans into demons, it is a sickness of demonic origin that can classify it as a mutation.
Acheri are types of demonic spirits that manifest as little girls. They appear to be among the lesser ranked, as they can be control by powerful psychics. Unlike typical demons, however, the Acheri are able to physically manifest as little children from their demonic smoke forms, as well take on a more monstrous appearance with gnarled faces, and sharp claws.
The Seven Deadly Sins are the seven demons who are said to be the manifestations of biblical impurities. It is unknown how the seven deadly sins were actually created, but the sins themselves said that they are only the personifications of the natural instincts of humans. The names of these demons are as follows: Envy, Lust, Greed, Pride, Gluttony, Sloth and Wrath. Despite having black-eyes, these demons have special powers unique to them, allowing them to manipulate the feelings / drives of their respective namesakes on unsuspecting humans.
Samhain is the "Lord of the Dead" and known as the origin of Halloween. He can only be conjured up once every 600 years, for which three victims must be killed in a blood ritual, the last of which must die on October 31st. If he is summoned, Samhain is capable of calling forth the dead such as ghosts and zombies, as well as being able to wipe out people with his own demonic energy. Samhain is one of the more unique demons encountered, as his eyes are a greyish blue, a color not seen in any other demons. His eyes, are also a weakness, as he cannot differentiate between a dead human and one with blood on their face. Sam Winchester theorized that Samhain could be immune to the demon-killing knife, though he only proved tolerance to the pain after Sam cut his arm.