Gorgons

“	I believe we are hunting a Gorgon. An ancient, cursed being, with an affinity for snakes and a hunger for human flesh.	”
	— Rowena in Ouroboros

The Gorgons are a type of demigods from the greek mythology.

Powers and Abilities

Paralyzing Poison - Gorgons possess a powerful paralyzing poison, the source of the myth about their turning people to stone. This poison is so potent that it can even affect a Seraphim.
Super Strength - Gorgons possess an incredible degree of strength, able to overpower humans with ease.
Telepathy - One gorgon showed the ability to read the mind of one of his victims and taunt him with his thoughts as the man attempted to deny what was happening to him.
Snake Communication - Gorgons can understand and communicate with snakes.
Invulnerability - Gorgons can only be killed by being decapitated with a silver blade.
Immortality - Being a race of demigods, they can potentially live forever.

Precognition - By eating the eyes of a human, a gorgon could see glimpses of the near future. By looking at a person, they could see their fate. Their power to see the immediate future was limited to that of humans and with a Seraphim and a Nephilim, one could not see them even when the Seraphim was standing next to a human in the event he foresaw. However, he could apparently foresee the future of the Nephilim when he was in front of the gorgon.

Gorgons possesses very few weaknesses.

Decapitation with a Silver Blade - The only known way to kill a gorgon is cut their head off with a silver blade.
Gorgon's Poison Antidote - Rowena was able to produce a antidote that neutralizes the Gorgon's Poison effect using Anti-Venom, however this antidote apparently do not work on Angels/Seraphim (or, at the very least, it takes effect on them much slower than it does on humans).
Angelic Beings - Noah's precognition didn't work on them, as he couldn't foresee Castiel (a Seraphim) and Jack's (a Nephilim) arrival.
- Nephilims - Besides being immune to Gorgon's precognition, since the Antidote apparently didn't work on a Seraphim like Castiel, in one occasion Jack was able to use his powers to neutralize the effect of the poison himself.

Sam says that Artemis, the greek goddess of the hunt is "who we'd pray to for courage when hunting the Gorgon or the Minotaur. Of course, she's not really worship worthy anymore, uh, having lost a step and all".
The Gorgon Tooth that appeared in the Season 13 episode "The Scorpion and The Frog" was quite large while the gorgon that appeared in the Season 14 episode "Ouroboros" was a human-sized being with regular teeth.
In "The Scorpion and The Frog" Sam was able to recognize immediately the fossilized tooth as being that of a Gorgon. However in "Ouroboros" nor he or anyone else were able to recognize the creature that they were after before Rowena told them.
The Gorgon in Greek myth were the three sisters, Stheno, Euryale, and Medusa, who had the power to turn anyone who looked at them to stone. In some tellings, Medusa, the youngest, was born a beautiful woman and served as a priestess to Athena. However, after breaking her vow of chastity by sleeping with Poseidon in Athena's temple, Medusa was transformed into a gorgon by the goddess.