Name Unknown

These two appear human but do not be fooled.  One of our operatives got too close once, and was engulfed by a gelatinous tentacle.

Grist

A shape shifter.  Comes in many guises.  He is likely  to wreak of spicy rum and chili peppers.  Rumored to be the earthbound incarnation of Baron Samedi, and Guede his own self.

The Goddess Lascivia

The Goddess Made Flesh.  Avoid at all costs.  She’ll eat you for breakfast, boy.  Wears a necklace of human souls, trapped forever in a state of unbearable pain.  She laughs at us.

Dr. Stone

No one knows what the fuck Dr. Stone is, but if he gets you, it’s all over.

It is rumored that he can smell through time.

Nucklavee

The Nuckelavee is a monster of unparalled evil. The old settlers said that were it not for the Mither o' the Sea restraining the foul beasts during the long summer months and their terror of fresh rainwater keeping them in check during winter, they would long ago have turned North America into an uninhabited desert. The reason for their serious objections to fresh water are unknown but are fortunately sufficient to keep them off the land whenever the heavens open and the blessed rain falls.

Although their home is thought to be the sea, the creatures are known to travel freely on land and it was on these excursions that they are most often encountered by mortals. When on land, Nucklavee ride a galloping steed that is as monstrous as he himself. Some tales have merged the two monsters so that the rider and horse become one, a vile hybrid of man and beast that is the Nuckelavee's true shape.

We can only speculate.  Few have seen a full Nuckleavee and lived to tell the tale.

From the few recorded decriptions of Nuckelavee's we know that his head is described as being much akin to a mans only "ten times larger" with an incredibly wide mouth that jutted out like that of a pig. He is hairless and has no skin so that the entire surface of the monster's body appears like raw and living flesh, from which the skin has been flayed. It is said that thick, black blood can be seen coursing through his veins and his sinewy muscles writhe with every movement made.

Nuckleavees were once men who went through a horrifying transformation.  No one can explain how the transformation comes about, but it starts with the victims head becoming loose upon his neck, and swelling larger than normal.  Choking noises are often made by the victim.  The head begins to move around by itself, seemingly without the victim’s control. 

The only way to stop a transformation this far along is to secure the head, and hold on for dear life.  If you let go, the victim will transform.

"If crops were blighted by sea-gust or mildew, if livestock fell over high rocks that skirt the shores, or if an epidemic raged among men, or among the lower animals, Nuckelavee was the cause of all. His breath was venom, falling like blight on vegetable, and with deadly disease on animal life."

Prion

Long Live The New Flesh

"...And out of the Desert of  Suppurating Sores shambled a thing with flesh of rotting beef and flames around and through it.  Rats and maggots made their home in its flesh....and it was called Prion, and it vowed to take the world into itself, and transform the world and its creatures into spongiform brains."

--The Revelation to Uncle Gus  chapter 8, verse 3

Cthulhu