The ghoul (Herophilus sapiens) is a natural scavenger, preferring to feed on dead and decaying flesh. They evolved in parallel with Homo sapiens, resulting in heavily overlapping ranges and histories. Ghouls have been responsible for a great many folk stories and legends around the world. Very few of them have been pleasant.
Concentrated efforts on the part of the Covenant of St. George resulted in the destruction of most of the ghouls in Europe and the Middle East before the end of the sixteenth century. The survivors scattered and hid, with many choosing to migrate to North America when the opportunity arose. Their populations have become largely integrated with the local human populations, making them harder to isolate and eliminate.
Ghouls are currently considered endangered, although everyone involved wishes they were rather more endangered than they currently are. We do not have a "shoot on sight" policy, as all creatures have a right to life, but when those creatures try to eat the neighbors, that right gets a little strained.
Ghouls are members of the family Hominidae, making them close relatives of Homo sapiens. This does not, unfortunately, keep them from eating humans. While they are primarily scavengers, increased cremation rates and improvements in mortuary security have led many ghouls to become predatory, choosing to eat slightly less flavorful live prey rather than going hungry. This is problematic, as their preference for human flesh remains unchanged. They are primarily nocturnal, but this seems to be a preference, rather than a biological need.
Internally, ghouls share the biological makeup of most members of family Hominidae. They are not particularly strong, swift, or otherwise enhanced. They do, however, possess teeth which are more similar to those of a shark than to any other known hominid. These teeth grow in multiple serrated rows, and will continue to grow over the course of the ghoul's lifetime. Some ghouls will break and replace as many as fifty complete sets of teeth.
Ghouls bear live young, with the average birthrate being close to the human norm. In times of privation, they will eat their young. We try not to think about that too hard.
Ghouls look very much like humans, as long as they avoid smiling and displaying their teeth. That's part of the problem.
Artwork by Kory Bing.