A ghoul could be considered the ‘missing link’ between zombies and vampires. Older than the zombies, ghouls are fist mentioned in the Templar Codex in 908 AD. Their origin appears to be Arabic, possibly diseased cannibals degrading into the undead. Ghouls spread slowly through Europe and were reported in China in the late 14th Century. They appeared in the New World in 1709, arriving with trade ships from the Netherlands.
Ghouls have free will and awareness, although the vast majority suffer from any number of mental derangements when they rise. They tend to be paranoid and psychotic, devoted to securing a safe haven and building an army of followers, living or otherwise. They can command zombies and are both stronger than an ordinary human, and more durable. They psychically exude a feeling of fear and despair that affects nearby humans and is probably the basis for their ability to control their zombie thralls. If they have fed recently, they are also able to regenerate, though silver and fire mitigate these advantages to some degree. They can be killed permanently by decapitation, a silver-caused mortal wound, or immolation.
One in every fifty zombie victims becomes a ghoul. Ghouls have a similar reproduction ratio as well, creating only one other ghoul in every twenty victims, but without creating any more zombies. Their bite carries an infection that, like the zombie strain is fatal, but takes longer to be so, usually 4-6 hours. This is usually a moot point as ghouls have a more ravenous hunger for human flesh. They decay more slowly, and are better able to disguise their condition than are zombies.