The first time Sam and Dean encountered them was when they took on the form of their long-lost half-brother Adam Milligan and his mother. They also appeared when Crowley attempted to have Sam and Dean fed to a pair of ghouls.
Ghouls are scavenger creatures that live in graveyards and traditionally feed on the flesh and blood of the dead. At times ghouls will change their diet and will feed on living humans instead of the dead. Ghouls can also take the form of any person they have eaten, whether the person is still alive or already dead.
The only thing that can kill a Ghoul is decapitation or complete destruction of the head.
- Shapeshifting - Ghouls have the power to transform into any human, though they can only transform into humans they've fed off of, regardless of whether they are still living or dead. Like shapeshifters, ghouls also obtain the memories of the person they are mimicking.
- Super speed - Ghouls are said to move faster than humans, at least enough to escape unseen after a surprise attack. In the episode "Two And A Half Men," after battling a monster in human form that moved with superhuman speed, Sam listed what creatures could move with supernatural speed; ghouls were first on the list. Sam and Dean learned later that they were hunting shapeshifters and the alpha shapeshifter.
- Super strength - Ghouls are stronger than humans. They can overpower a human, but they can also be fought off. In "Caged Heat", Dean was able to temporarily hold off two ghouls without using guns or other kinds of weapons. As such they are amongst the weaker monsters.
- Enhanced durability - Ghouls are more durable than humans, as one was able to take a shotgun blast to the torso and was only stunned. However, they are far from invulnerable.
- Decapitation - Complete removal or destruction of the head is lethal to a ghoul.
- Vamptonite - Edgar states the leviathan additive will kill ghouls as well as vampires. (There Will Be Blood)
- Extreme Brain Damage - Enough damage to the head, even without decapitation, can kill a Ghoul.
- The Colt - The Colt can kill almost anything and could presumably kill a ghoul.
- Season 4
- Season 6
- Season 9
- Season 12
- Celebrating The Life Of Asa Fox (mentioned only)
- In popular culture, the word "ghoul" is often used for an undead creature that eats freshly buried corpses. However, in Supernatural, ghouls are not undead but a type of monster.
- The actual ghouls in Islamic lore aren't always dead, and are often a devilish form of jinn or demon, believed to be sired by Iblis.
- Although it's never been stated on the show, there's a possibility that ghouls are a subtype of djinn, since their method of feeding is similar to how djinn feed on people. In real lore, ghouls are believed to be a type of jinn, as well as the offspring of Iblis.
- In Celebrating The Life Of Asa Fox, Jody Mills reveals that she first met hunter Asa Fox when he came to the Sioux Falls area on a ghoul hunt. During the hunt, Asa identified himself as Agent Fox Mulder to Jody who saw through the lie and helped him kill the ghouls.