Fifteen or so monsters we’ve met and other entities:

1. Demons
2. Djinn
3. Ghost (also Vengeful Spirit)
4. Ghoul
5. Hellhounds
6. Leviathan
7. Phoenix
8. Rugaroo
9. Shapeshifter (aka Shifter)
10. Skinwalker
11. Vampire
12. Vetala
13. Wendigo
14. Werewolf
15. Witch

• People (see The Benders [1.15])
• Clowns (see Sam, Everybody Loves a Clown [2.2])
• Jefferson Starships (aka Starships) (see Mommy Dearest [6.19])
• Khan Worm (see And Then There Were None [6.16])
• Faeries
• Leprechaun
• Zombie (but not really – see Dead Men Don’t Wear Plaid [5.15])
• Trickster (again, not really, but spoilers) (see Tall Tales [2.15])

Biblical:

• G-d
• Lucifer
• Michael
• Raphael
• Gabriel
• Lilith
• Eve
• Ezekiel
• Gadreel

Who am I forgetting?!